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Report 2005-02: The Pricing Performance of
Market Advisory Services in
Corn and Soybeans Over 1995-2003: A Non-Technical Summary
March 2005 
Scott H. Irwin,
Darrel L. Good,
Joao Martines-Filho and
Lewis A. Hagedorn
[1]
Copyright
2005 by Scott H. Irwin, Darrel L. Good, Joao Martines-Filho and
Lewis A. Hagedorn . All rights reserved. Readers may make verbatim
copies of this document for non-commercial purposes by any means,
provided that this copyright notice appears on all such copies.
Introduction
Farmers in the US consistently identify price and income risk as one of the greatest management challenges they face. Surveys suggest that numerous farmers view professional market advisory services as an important tool in managing price and income risk. As a result, there is a need to develop an ongoing "track record" of the performance of market advisory services to assist farmers in identifying successful alternatives for marketing and price risk management. The Agricultural Market Advisory Service (AgMAS) Project was initiated in 1994 with the goal of providing such information.
The purpose of this research
report is to summarize the pricing performance of professional market
advisory services for the 1995-2003 corn and soybean crops. The
results for 1995-2001 were released in earlier AgMAS research reports,
while the results for the 2002 and 2003 crop years are new. Complete
details on data collection, computation of net advisory prices and
benchmarks and pricing performance tests can be found in the full
AgMAS research report by Irwin et al. (2005).
At least 23 advisory programs
are included in the evaluations for each commodity and crop year.
While the sample of advisory services is non-random, it is constructed
to be generally representative of the majority of advisory services
offered to farmers. Two indicators of pricing performance are presented.
The first indicator is the proportion of advisory programs that
beat benchmark prices. The second indicator is the average price
of advisory programs relative to benchmarks. Both market and farmer
benchmarks are considered in the evaluations.
At the outset, it is important
to point out that only nine crop years are available to analyze
market advisory service pricing performance. From a purely statistical
standpoint, samples with ten or fewer observations typically are
considered "sparse." On the surface, this suggests the
sample may not contain enough information to draw conclusions about
advisory service pricing performance. There are several reasons
why this may not be the case. First, Anderson (1974) explored the
reliability of agricultural return-risk estimates based on sparse
data sets and found the surprising result that even as few as three
or four observations can be useful. Second, even though the number
of crop years is limited, at least 23 advisory programs are tracked
for each crop year. This has the potential to substantially increase
the information provided by the sample. Third, from a practical,
decision-making standpoint, samples with seven observations often
are considered adequate to reach conclusions. The results of university
crop yield trials represent a well-known example. A typical presentation
of the results includes only current year yields and two-year or
three-year averages. In many cases, even the two-year and three-year
averages cannot be presented because of turnover in the varieties
tested from year-to-year. Despite the limitations, this type of
yield trial data is widely used by farmers in making variety selections.
On balance, then, it seems reasonable to argue that the seven years
of data currently available on advisory service pricing performance
may be used to make some careful conclusions. Caution obviously
is in order given the possibility of results being due to random
chance in a relatively small sample of crop years.

Computing the Returns to Marketing
Advice
In order to evaluate the returns
to the marketing advice generated by advisory services, the AgMAS
Project purchases a subscription to each of the programs offered
by a service[2].
The information is received electronically via websites, e-mail
or satellite service (DTN). Staff members of the AgMAS Project read
the daily information provided by each advisory program. As a result,
"real-time" recommendations are obtained.
After AgMAS staff collects the
stream of recommendations for a particular crop year, all of the
(filled) recommendations are aligned in chronological order. The
advice for a given crop year is considered to be complete for each
advisory program when cumulative cash sales of the commodity reach
100%, all futures positions covering the crop are offset, all option
positions covering the crop are either offset or expire and the
advisory program discontinues giving advice for that crop year.
In order to produce a consistent and comparable set of results across
the different advisory programs, certain explicit assumptions are
made. These assumptions are intended to accurately depict "real-world"
marketing conditions facing a representative central Illinois corn
and soybean farmer. Several key assumptions are: i) with a few exceptions,
the marketing window for a crop year runs from September before
harvest through August after harvest, ii) on-farm or commercial
physical storage costs, as well as interest opportunity costs, are
charged to post-harvest sales, iii) brokerage costs are subtracted
for all futures and options transactions and iv) Commodity Credit
Corporation (CCC) marketing loan recommendations made by advisory
programs are followed wherever feasible. Based on these and other
assumptions, the net price received by a subscriber to a market
advisory program is calculated for the 1995-2003 corn and soybean
crops. It should be interpreted as the harvest-equivalent net price
received by a farmer because post-harvest sales are adjusted for
physical storage and interest opportunity costs.
The next step in evaluating pricing
performance is specification of objective standards of performance.
These objective standards typically are referred to as "benchmarks."
It is commonplace to compare performance to benchmarks in other
economic contexts, such as financial investments. Some of the best-known
stock investment benchmarks are the Dow-Jones Industrials Index,
S&P 500 Index and the Wilshire 5000 Index.
Two different types of benchmarks
are developed for the performance evaluations. Efficient market
theory implies that the return offered by the market is the relevant
benchmark. In the context of this study, a market benchmark should
measure the average price offered by the market over the pricing
window of a representative farmer who follows advisory program recommendations.
Both a 24-month and a 20-month market benchmark are specified in
order to test the fragility of performance results to different
market benchmark assumptions. The first market benchmark averages
cash price over the entire 24-month marketing window, which begins
on September 1 of the year prior to harvest and ends on August 31
of the year after harvest. The second market benchmark is computed
by simply deleting the first four months of the 24-month pricing-window
from the computations of the average market price. Behavioral market
theory suggests that the average return actually achieved by market
participants is an appropriate benchmark. In the context of the
present study, a behavioral benchmark should measure the average
price actually received by farmers for a crop. A farmer benchmark
is specified based upon the USDA average price received series for
corn and soybeans in Illinois. All benchmarks are computed using
the same assumptions applied to advisory program track records.
Note that the same simulation assumptions applied to advisory service
track records (e.g., storage costs) are applied to the market and
farmer benchmarks.

Net Advisory Prices and Benchmarks
for 1995 - 2003
Net advisory prices and benchmarks
for the 1995-2003 crop years are reported in Tables
1 and 2. In order to obtain a consistent set of net advisory
prices and benchmarks for the entire sample period, commercial storage
costs are assumed. It is not possible to present parallel results
assuming on-farm variable costs of storage, because the AgMAS Project
first computed net advisory prices and benchmarks under this alternative
storage cost assumption for the 2000 crop year. See the previously
mentioned AgMAS research report by Irwin et al. (2005) for 2000-2003
crop year results that assume on-farm variable costs of storage.
Also note that some of the market advisory services included in
the tables are not evaluated for all nine crop years.
Table 1
shows the average advisory price for corn ranges between $1.99 per
bushel in 2001 and $3.03 per bushel in 1995 (based on commercial
storage costs). Range statistics reveal that net advisory prices
for corn vary substantially within individual crop years. The most
dramatic example is 1995, where the minimum is $2.29 per bushel
and the maximum is $3.90 per bushel. Even in years with less market
price volatility, it is not unusual for the range of prices across
advisory programs to be near a dollar per bushel. The three alternative
benchmark prices for corn are shown at the bottom of Table
1. The variation in benchmark prices from year-to-year is similar
to that of average net advisory prices. However, there can be substantial
differences in benchmark prices for a particular crop year. For
example, the 24-month market benchmark in 1998 is $2.24 per bushel,
while the farmer benchmark is only $1.97 per bushel. These data
suggest performance results for corn may be sensitive to the selected
benchmark.
As reported in Table
2, the average advisory price for soybeans ranged from $5.24
per bushel in 2002 to $7.27 per bushel in 1996 (based on commercial
storage costs). Similar to corn, the range of individual net advisory
prices within a crop year is substantial. The most dramatic example
is 2003, where the range in advisory prices is just under $4 per
bushel. The three alternative benchmark prices for soybeans are
shown at the bottom of Table 2. The variation
in soybean benchmark prices from year-to-year is similar to that
of average net advisory prices. Once again, there can be substantial
differences in benchmark prices for a particular crop year.
Since many subscribers to market
advisory services produce both corn and soybeans, it is relevant
to examine a combined measure of corn and soybean pricing performance
for each market advisory program. One way to aggregate the results
is to calculate the per-acre revenues implied by the pricing performance
results. The per-acre revenue for each commodity is found by multiplying
the net advisory price for each market advisory service by the actual
central Illinois corn or soybean yield for each year. A simple average
of the two per acre revenues is then taken to reflect a farm that
uses a 50/50 rotation of corn and soybeans.
Table 3
contains the combined corn and soybeans revenue results (based on
commercial storage costs). The lowest average advisory revenue,
$287 per acre, occurred in 2001, while the highest average advisory
revenue, $369 per acre, occurred in 1996. Given the results for
corn and soybeans, the large range of individual advisory revenues
within a crop year is not surprising. Nonetheless, it is startling
to see the possible economic impact of following the best versus
the worst performer in a given crop year. For example, in three
of the nine crop years (1995, 1999 and 2000) the range in advisory
revenue exceeds $100 per acre.

Advisory Service Pricing Performance
Over 1995-2003
Before considering the performance
evaluation results, two important issues need to be discussed. First,
the results presented in this section of the report address the
performance of market advisory programs as a group. In other words,
average pricing performance across all programs is considered. This
is a different issue than the pricing performance of a particular
advisory program. Simply put, it is inappropriate to make performance
inferences for an individual advisory program based on aggregate
results. Second, farmers subscribe to market advisory programs for
a variety of reasons. For example, marketing information and market
analysis are the two highest rated uses of market advisory programs
by farmer-subscribers (Pennings et al., 2004). While the quality
of marketing information and market analysis is likely to be positively
correlated with the returns to marketing recommendations, this does
not necessarily have to be the case. It is possible that advisory
programs provide valuable information and analysis to farmer-subscribers,
yet fail to exhibit superior pricing performance.
Directional Performance
The first, and simplest, indicator
of pricing performance is the proportion of advisory programs that
beat the market or farmer benchmarks. Positive performance is indicated
if the proportion of advisory programs beating a benchmark exceeds
50%, the proportion one would observe if advisory performance is
random, like flipping a fair coin. A noteworthy feature of this
"directional" indicator is that it is not influenced by
extremely high or low advisory prices or revenue.
The proportion of advisory programs
in corn, soybeans and 50/50 advisory revenue above the benchmarks
over 1995-2003 is presented in Table 4.
Note that average proportions for 1995-2003 are computed over the
full set of advisory programs, and therefore, do not necessarily
equal the average of the individual crop year proportions. This
"grand" average equally weights each of the net advisory
prices or revenues in the sample, whereas an average of the individual
crop year averages would equally weight the crop years. The first
average is preferred for the present purpose as it implies an equal
probability of selecting an individual advisory program across the
entire sample.
Considering corn first (Panel
A: Table 4), there is some variation in
the proportion of net advisory prices above the two market benchmarks
for individual crop years, particularly 1998, but the patterns are
similar overall. There also does not appear to be any discernable
trend in the proportions for either benchmark over the nine crop
years. The average proportion for 1995-2003 is 50% versus the 24-month
benchmark and 59% versus the 20-month benchmark, indicating a zero
to marginal chance of advisory prices in corn beating market benchmark
prices. In contrast, the proportion of net advisory prices above
the farmer benchmark equals or exceeds 50% each crop year. The average
proportion above the farmer benchmark over 1995-2003 is 68%. This
is larger than the average proportions versus the market benchmarks
and indicates a better chance of market advisory programs generating
net prices higher than the farmer benchmark. However, there has
been a noticeable downtrend in proportions versus the farmer benchmark
since 1998.
Moving to soybeans (Panel B:
Table 4), there is more variation in the
proportion of net advisory prices above the two market benchmarks
for individual crop years. Particularly sharp differences are observed
in 1998 and 1999, where the spread between proportions for the two
market benchmarks is 45 and 36 percentage points, respectively.
No clear trend is apparent for the proportions versus either market
benchmark. Despite these differences for individual crop years,
the average proportions for 1995-2003, 65% versus the 24-month benchmark
and 72% versus the 20-month benchmark, both indicate a better than
average chance of advisory prices beating market benchmark prices
in soybeans. The average proportion above the farmer benchmark over
1995-2003 is 54%. This indicates a small chance of market advisory
programs generating net prices in soybeans higher than the farmer
benchmark. In addition, there has been a sharp downtrend in proportions
versus the farmer benchmark since 1998.
Given the combined nature of
50/50 advisory revenue, it is not surprising that revenue proportions
(Panel C: Table 4) typically are between
those of corn and soybeans. The average proportion for 1995-2003
is 59% versus the 24-month benchmark and 68% versus the 20-month
benchmark, indicating a marginal to better than average chance of
advisory revenue beating market benchmark revenue. The average proportion
above the farmer benchmark over 1995-2003 is 62%. This indicates
a moderate chance of advisory revenue beating farmer benchmark revenue.
Mirroring the results for corn and soybeans, a sharp downtrend is
observed in proportions versus the farmer benchmark since 1998.
It is interesting to note that 100% of the advisory programs in
1998 generated revenue that exceeded the farmer benchmark, despite
the fact that less than 100% did so in corn and soybeans. This simply
reflects a situation where some programs had gains above the farmer
benchmark in one commodity that more than offset the losses below
the benchmark in the other commodity.
Overall, the directional performance
results over 1995-2003 suggest several key findings. First, advisory
programs in corn do not consistently beat market benchmarks, but
tend to consistently beat the farmer benchmark. Second, advisory
programs in soybeans exhibit just the opposite pattern, consistently
beating the market benchmarks but not the farmer benchmark. Third,
in terms of 50/50 revenue, advisory programs show marginal consistency
in beating both the market benchmarks and the farmer benchmark.
So, the results provide mixed performance evidence with respect
to both the market benchmarks and the farmer benchmark.

Average Price Performance
The second indicator of pricing
performance is the difference between the average price of advisory
programs and the market or farmer benchmarks. This indicator takes
into account both the direction and magnitude of differences from
the benchmarks. The results found in Tables
5 and 6 basically tell the same story as those based on the
proportion beating the benchmarks. Average differences from market
benchmarks for corn over 1995-2003 (panel A: Table
5) are small, ranging from 1 to 3¢ cents per bushel.[3]
At 8¢ cents per bushel, the average difference from the farmer
benchmark for corn is larger. Average differences from market benchmarks
for soybeans over 1995-2003 (panel B: Table
5) are substantial, ranging from 14 to 16¢ per bushel.
In contrast, the average difference from the farmer benchmark for
soybeans is -1¢ per bushel. Average differences for 50/50 advisory
revenue range from $4 to 7 per acre for market benchmarks over 1995-2003
(Table 6). The average revenue difference
versus the farmer benchmark is similar at $7 per acre. Note that
the average differences can mask considerable variability across
the benchmarks within a crop year and across crop years. A dramatic
example of this occurred in 2003 for soybeans (Panel B: Table
5), where the average difference from the 24-month market benchmark
is +27¢ per bushel, while the average difference from the farmer
benchmark is -105¢ per bushel. [4].
An important consideration is
the size of the average differences versus the farmer benchmark
from an economic decision-making perspective. The average advisory
return relative to the farmer benchmark is $7 per acre, or about
two percent of average farmer benchmark revenue. Even though this
return is small and entirely from corn, it nonetheless represents
a non-trivial increase in net farm income (defined as returns to
farm operator management, labor and capital), typically about $50
per acre for grain farms in Illinois (Lattz, Cagley and Raab, 2004).
The comparison does not account for yearly subscription costs, which
is not a major problem because subscription costs are quite small
relative to revenue. Subscription costs are only 18¢ per acre
for a 2,000 acre farm and 72¢ per acre for a 500 acre farm.
A more serious issue is fully accounting for the cost of implementing,
monitoring and managing the marketing strategies recommended by
advisory programs. Such costs are difficult to measure, but may
well be substantial (Tomek and Peterson, 2001).
When viewing statistical test results, it is always important to
assess whether the nature of the sample information or the comparisons
bias the results in one direction or the other. Price patterns represent
one potential source of bias in the performance results. It turns
out there are systematic patterns in corn and soybean price movements
during the sample period that may have an important impact on the
tests results. Figure 1 shows the average
pattern of corn and soybean prices over the 24-month marketing window
for the 1995-2003 crop years. These charts are based on the same
harvest equivalent forward and spot cash prices (including LDP/MLGs)
used to compute net advisory prices and the market benchmarks. The
downward trend in corn prices over the 24-month window is substantial,
with the high in pre-harvest prices about 55¢ per bushel higher
than the post-harvest low (net of storage costs). A marketing strategy
in corn that systematically priced more heavily in the pre-harvest
period relative to the post-harvest period would have generated
much higher returns than a strategy that did not. The price pattern
in soybeans is noticeably different, with prices roughly flat for
the pre-harvest period and then rising sharply through the post-harvest
period before dropping off sharply. In this case, a marketing strategy
that systematically priced more heavily in the first two-thirds
of the post-harvest period would perform the best.
Next, consider the average "marketing
profiles" found in Figure 2 for corn
and soybeans over the 1995-2001 crop years.[5]
The marketing profiles show the average amount of corn and soybean
crops priced (sold) by market benchmarks, advisory programs and
farmers on a cumulative basis, each day over the two-year period
beginning in September of the year before harvest and ending August
of the year after harvest. Since USDA marketing weights represent
grain purchases, which are not necessarily the same as pricing weights
due to farmers' use of forward contracts, the marketing profile
for farmers is only hypothetical. It is based on a similar marketing
window as the market benchmarks and advisory programs, but reflects
substantially less pricing in the pre-harvest period. In light of
the downward price trend in corn, the marketing profiles reveal
why market benchmarks and advisory programs in corn generated higher
average prices than the farmer benchmark over the last nine crop
years. More than likely, farmers priced much less of the corn crop
in the pre-harvest period than the market benchmarks or advisory
programs. In contrast, the price trends in soybeans favored the
marketing pattern of farmers, allowing them to perform about the
same as advisory programs and actually outperform the market benchmarks.
In sum, pricing performance depends
on a complex set of variables that include corn and soybean price
behavior, advisory program strategies and the marketing behavior
of farmers. It is on open question whether the behavior of these
variables in the last nine crop years provides a reliable guide
for the future. The persistence of downward price trends frequently
observed over 1995-2003 in corn is an especially hotly debated issue.
Further study is needed to determine whether the price patterns
observed over 1995-2003 are representative of patterns in the long-run.
This information would help to clarify whether market conditions
during 1995-2003 bias performance comparisons in any particular
direction.
Please note that the AgMAS research
report by Irwin et al. (2005) contains complete pricing performance
results. In particular, additional results show that consideration
of risk weakens performance results in some cases and that it is
difficult to predict the pricing performance of advisory programs
from past performance.

Summary and Conclusions
The purpose of this research
report is to summarize the pricing performance of professional market
advisory services for the 1995-2003 corn and soybean crops. The
first indicator of performance presented in the report is the proportion
of advisory programs that beat benchmark prices. Between 50 and
59% of the programs in corn have net advisory prices above market
benchmarks over 1995-2003, indicating a zero to marginal chance
of advisory prices in corn beating market benchmark prices. In contrast,
68% of the programs have prices above the farmer benchmark in corn.
Between 65 and 72% of advisory programs in soybeans have advisory
prices above the market benchmarks over 1995-2003, suggesting a
better than average chance of advisory prices beating market benchmark
prices in soybeans. The proportion of advisory programs above the
farmer benchmark in soybeans is only 54%, indicating a small chance
of programs generating net prices in soybeans higher than the farmer
benchmark. Between 59 and 68% of advisory programs have revenue
above the market benchmarks over 1995-2003, while 62% have revenue
above the farmer benchmark. This indicates a moderate chance of
advisory revenue beating farmer benchmark revenue. Overall, the
directional test results provide mixed performance evidence with
respect to the market benchmarks and the farmer benchmark.
The second indicator is the difference
between the average price of advisory programs and the market or
farmer benchmarks. The results basically tell the same story as
those based on the proportion beating the benchmarks. Average differences
from market benchmarks for corn over 1995-2003 are small, ranging
from one to three cents per bushel. At 8¢ per bushel, the average
difference versus the farmer benchmark for corn is larger. Average
differences from market benchmarks for soybeans over 1995-2003 are
substantial, ranging from 14 to 16¢ per bushel. In contrast,
the average difference from the farmer benchmark for soybeans is
-1¢ per bushel. Average differences for advisory revenue range
from $4 to 7 per acre for market benchmarks over 1995-2003. The
average revenue difference versus the farmer benchmark is $7 per
acre.
Overall, the performance results
over 1995-2003 suggest several key findings. First, advisory programs
in corn do not consistently beat market benchmarks, but tend to
consistently beat the farmer benchmark. Second, advisory programs
in soybeans exhibit just the opposite pattern, consistently beating
the market benchmarks but not the farmer benchmark. Third, in terms
of 50/50 revenue, advisory programs show marginal consistency in
beating both the market benchmarks and the farmer benchmark. So,
the results provide mixed performance evidence with respect to both
the market benchmarks and the farmer benchmark.
In conclusion, the results of
this study provide an interesting picture of the performance of
market advisory programs in corn and soybeans. There is limited
evidence that advisory programs as a group outperform market benchmarks,
particularly after considering risk. This supports the view that
grain markets (cash, futures and options) are efficient with respect
to the types of marketing strategies available to farmers over the
view that grain markets are inefficient and provide substantial
opportunities for farmers to gain additional profits through marketing.
The evidence is more positive with respect to the farmer benchmark,
even after taking risk into account. This raises the possibility
that even though advisory services do not "beat the market,"
they nonetheless provide the opportunity for some farmers to improve
performance relative to the market. Mirroring debates about stock
investing, the relevant issue is then whether farmers can most effectively
improve marketing performance by pursuing "active" strategies,
like those recommended by advisory services, or "passive"
strategies, which involve routinely spreading sales across the marketing
window. Recently, a number of grain companies began offering averaging
or "indexing" contracts that allow farmers to easily implement
a passive approach to marketing. The rising interest in these new
marketing contracts suggests the potential for historic changes
in the approach farmers' use to market crops.

References
Anderson, J.R. "Sparse Data,
Estimational Reliability, and Risk-Efficient Decisions." American
Journal of Agricultural Economics, 55(1974): 564-572.
Colino, E.V., S.M. Cabrini, S.H. Irwin, D.L. Good and J.Martines-Filho.
"Advisory Service Marketing Profiles for Soybeans in 2001."
AgMAS Project Research Report 2004-02, Department of Agricultural
and Consumer Economics, University of Illinois at Urbana-Champaign,
April 2004. (http://www.farmdoc.uiuc.edu/agmas/reports/index.html)
Colino, E.V., S.M. Cabrini, S.H. Irwin, D.L. Good and J.Martines-Filho.
"Advisory Service Marketing Profiles for Corn in 2001."
AgMAS Project Research Report 2004-01, Department of Agricultural
and Consumer Economics, University of Illinois at Urbana-Champaign,
April 2004. (http://www.farmdoc.uiuc.edu/agmas/reports/index.html)
Irwin, S.H., D.L. Good., J. Martines-Filho, and L.A. Hagedorn. "The
Pricing Performance of Market Advisory Services in Corn and Soybeans
Over 1995-2003." AgMAS Project Research Report 2005-01, University
of Illinois at Urbana-Champaign, March 2005. (http://www.farmdoc.uiuc.edu/agmas/reports/index.html)
Lattz, D.H., C.E. Cagley and D.D. Raab. Summary of Illinois Farm
Business Records for 2001, Circular 1384, University of Illinois
Extension, 2002.
Martines-Filho, J., S.H. Irwin, D.L. Good, S.M. Cabrini, B.G. Stark,
W. Shi, R.L. Webber, L.A. Hagedorn and S.L. Williams. "Advisory
Service Marketing Profiles for Corn Over 1995-2000," AgMAS
Project Research Report 2003-03, Department of Agricultural and
Consumer Economics, University of Illinois at Urbana-Champaign,
June 2003a. (http://www.farmdoc.uiuc.edu/agmas/reports/index.html)
Martines-Filho, J., S.H. Irwin, D.L. Good, S.M. Cabrini, B.G. Stark,
W. Shi, R.L. Webber, L.A. Hagedorn and S.L. Williams. "Advisory
Service Marketing Profiles for Soybeans Over 1995-1999," AgMAS
Project Research Report 2003-04, Department of Agricultural and
Consumer Economics, University of Illinois at Urbana-Champaign,
June 2003b. (http://www.farmdoc.uiuc.edu/agmas/reports/index.html)
Pennings, J.M.E., O. Isengildina, S.H. Irwin and D.L. Good. "Modeling
the Impact of Market Advisory Services on Producers' Decisions."
Journal of Agricultural and Resource Economics, 29(2004):308-327.
Tomek, W.G. and H.H. Peterson. "Risk Management in Agricultural
Markets: A Review." Journal of Futures Markets, 21(2001):853-985.

Appendix:
A Cautionary Note on the Use of AgMAS Net Advisory Prices and Benchmarks
The net advisory prices and
benchmarks computed by the AgMAS Project are designed to reflect
"real-world" marketing conditions and assure that net
advisory service prices and benchmarks are computed on a rigorously
comparable basis. This latter point is especially important, as
performance evaluations must compare "apples to apples"
and not "apples to oranges." Comparison problems may arise
if prices computed by an individual farmer, or another market advisory
service, are compared to AgMAS net advisory prices and benchmarks.
First, and foremost, AgMAS net
advisory prices and benchmarks are stated on a harvest equivalent
basis. This means that spot cash prices for post-harvest sales are
adjusted for storage costs, which include physical storage charges,
shrinkage charges and interest opportunity costs. The impact of
this assumption is illustrated in the top panel of Figure
A1 for corn and the bottom panel for soybeans. The top line
in each chart shows the 2003 harvest cash price for each crop (corn:
$2.04 per bushel; soybeans: $6.66 per bushel). The bottom line reflects
a cash sale at the same harvest price one to eleven months after
harvest, with the cash price adjusted for commercial costs of storage.
As a specific example, consider a six-month storage horizon for
corn. In this case, the cash price of the sale six-months after
harvest is assumed to be $2.04 per bushel, the same as the harvest
cash price (equivalent to saying cash prices do not change over
the six-month storage period). However, the harvest equivalent price
for the sale six months after harvest is only $1.75 per bushel after
adjusting for commercial storage costs. Thus, the difference between
unadjusted and adjusted post-harvest prices in this example is 29¢
per bushel, a substantial difference by any standard. The magnitude
of the difference is larger for longer storage horizons and for
soybeans relative to corn. Note also that the difference will not
be as large if on-farm variable costs of storage are assumed instead
of commercial costs.
This discussion should make clear
the potential pitfalls in comparing the unadjusted average cash
price for an individual farmer or another market advisory service
to the harvest equivalent advisory prices and benchmarks computed
by the AgMAS Project. If such a comparison is made, it is not difficult
to imagine a scenario where it is mistakenly concluded that the
performance of the farmer or market advisory service is superior
to the advisory services, market benchmarks and farmer benchmarks
included in the AgMAS Project.
Second, AgMAS evaluations assume
a particular geographic location. Specifically, the evaluation is
designed to reflect conditions facing a representative central Illinois
corn and soybean farmer. This means comparisons made by farmers
or advisory services in other areas of the US may not be valid,
because yields and basis patterns may be quite different. The differences
in yields and basis patterns could have a substantial impact on
prices computed for farmers or advisory services in another area.
The resulting bias could be either up or down relative to AgMAS
advisory prices and benchmarks, depending on local conditions.
Third, wherever feasible, marketing
loan recommendations from advisory programs are followed by the
AgMAS Project. Consequently, marketing loan payments or benefits
are incorporated into net advisory prices. Market and farmer benchmark
prices also include marketing loan payments or benefits. Hence,
it would not be appropriate to compare prices for individual farmers
or another market advisory service if marketing loan payments or
benefits are not included in the prices or included in some other
way.
In sum, it is inappropriate
to directly compare prices for individual farmers or another market
advisory service to AgMAS net advisory prices or benchmarks unless
the same assumptions are used. To make valid comparisons, AgMAS
assumptions regarding storage costs, yield, basis, and marketing
loans have to be applied.

Endnotes
[1]
Scott H. Irwin is the Laurence J. Norton Professor of Agricultural
Marketing in the Department of Agricultural and Consumer
Economics at the University of Illinois at Urbana-Champaign.
Darrel L. Good is a Professor in the Department of Agricultural
and Consumer Economics at the University of Illinois at
Urbana-Champaign. Joao Martines-Filho is a Professor in
the Escola Superior de Agricultura Luiz de Queiroz (ESALQ)
at the University of São Paulo, Brazil and former
Manager of the AgMAS and farmdoc Projects in the Department
of Agricultural and Consumer Economics at the University
of Illinois at Urbana-Champaign. Lewis A. Hagedorn is a
former graduate research assistant with the AgMAS Project
in the Department of Agricultural and Consumer Economics
at the University of Illinois at Urbana-Champaign. The authors
gratefully acknowledge the research assistance of Wei Shi,
Silvina Cabrini, and Evelyn Colino; AgMAS graduate research
assistants in the Department of Agricultural and Consumer
Economics at the University of Illinois at Urbana-Champaign.
Invaluable assistance with estimating on-farm storage costs
was provided by Kevin Dhuyvetter, Department of Agricultural
Economics, Kansas State University, Lowell Hill, Department
of Agricultural and Consumer Economics at the University
of Illinois at Urbana-Champaign, Marvin Paulsen, Department
of Agricultural Engineering at the University of Illinois
at Urbana-Champaign, and Dirk Maier, Department of Agricultural
and Biological Engineering, Purdue University. Helpful comments
on this research report were received from members of the
AgMAS Project Review Panel.
[2]The term "advisory program" is used because
several advisory services have more than one distinct marketing
program.
[3] Differences are calculated as advisory price minus
benchmark price. So, a positive difference indicates an
advisory price above the benchmark price and vice versa.
[4]To facilitate direct comparisons across corn, soybeans
and advisory revenue, average percentage differences for
1995-2003 also are computed. Average differences between
the advisory programs and benchmarks for corn are 0.2%,
1.8% and 4.1% for the 24-month market, 20-month market and
farmer benchmarks, respectively. The same average differences
for soybeans are 2.7%, 2.6% and 0.6% and for revenue 1.3%,
2.2% and 2.6%, respectively.
[5]A detailed explanation of the construction of the
marketing profiles and results for individual advisory programs
and crop years can be found in Martines-Filho et al. (2003a,
2003b) and Colino et al. (2004a, 2004b). Note that these
reports do not contain marketing profiles for the 2002 and
2003 crop years. The AgMAS Project will compute the 2002
and 2003 profiles at a later date.
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