The Adoption of Agricultural Technology - Food Security Group

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Predicted adoption probabilities in the probit model are calculated inexactly the same way, except that F(b'x) in this case represents thecumulative standard normal probability distribution. The mathematicalform of the normal distribution is relatively complex, but values of F(b'x)can be found easily enough in standard probability tables.In some instances one might want to analyze not only adoption but also theextent or intensity of adoption. For example, one might want to estimateboth the probability that a farmer uses fertilizer and the rate of applicationas well. A commonly used model in this case is the tobit model. Tobit, likeprobit, is based on the normal distribution. As in probit or logit, coefficientsare estimated for the independent variables thought to be relevant. Tobitestimates also include the standard error of the regression s, which is anestimate of the standard deviation of the error term in the regressionmodel.Tn a tobit model, the predicted probability of adoption for a farmer withcharacteristics x is estimated by F(b'x/s), where b, x, and s are defined asabove, and F is the cumulative standard normal distribution function. Theexpected value of the application rate Y (or total amount used, dependingon the dependent variable used in the regression) is estimated byE(Y) = F(b'x/s)(b'x) + sf(b'x/s) ,where f is the probability density function for the standard normaldistribution.The expected value of Y, the application rate or total amount used, giventhat Y>O (Le., that the farmer is an adopter), is estimated byE(Y:Y>O) = b'x + Sf(b'x/ s)F(b'x!s)As with the cumulative standard normal distribution, the standard normaldensity function is also easily found in probability tables.-80Maddala (1983) is a good source of information on logit, probit, and tobitmodels. Multivariate analytical techniques are available in several softwarepackages for personal computers. It is thus quite easy to enter data on alarge number of variables and obtain long printouts and an impressive listof coefficients and related significance levels. But just as with the simpleranalytical techniques, the responsibility for interpreting the results restswith the researcher. A result that shows that certain variables areassociated with adoption says nothing about the causal links among those
variables. And a high significance level says nothing about the importanceof the relationship. This warning is especially relevant for multivariateanalyses, where computer technology makes it possible to examine dozensof variables. It must be remembered that a significance level of 10% meansthat the observed association has a one in ten chance of occurring atrandom. If we were to include 15 or 20 independent variables in anequation, we would expect that a couple of them would appear"significant" just by chance, especially if we ran several regressions withdifferent combinations of variables. (This warning is of course equallyvalid for the practice of analyzing 15 or 20 single-variable relationshipsuntil something appears that is "significant.") A summary of some of theseanalytical problems related to understanding the adoption of soilconservation is presented by Lockeretz (1990).Even sophisticated analytical techniques have severe limitations in theirability to disentangle complex relationships among a number of variables.The purpose of analyZing adoption patterns should be to identify a few keyrelationships or factors that not only can help us to understand theadoption process, but can help to make the research and extension effortmore efficient in the future. The emphasis should thus be on simpleanalyses and clear presentations (Casley and Kumar 1988). We should alsoremember that we are limited in our ability to understand adoption notonly by the statistical techniques at hand, but most of all by the skill withwhich we frame the questions in our adoption study and the quality of thedata that are generated.SummaryAdoption studies often attempt to analyze and understand the observedadoption patterns. In these cases, a~option survey analysis can includeboth an examination of farmers' opfnions and observations, and a statisticalcomparison of adoption measures with characteristics of the farmer or thefarming system. Farmers' decisions regarding a new technology are oftenquite complex, and the purpose of an analysis is to try to use a range ofstatistical procedures to identify the most important factors that influenceadoption. The analysis will be successful only if the information can beused to help improve the efficiency of subsequent technology generationand diffusion efforts.81
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I Chapter 1AdoptionStudiesWhy Study
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emphasis on participatory research
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of adoption study must be done with
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-7some idea of the degree to which
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80 2. tudl Used to Assess Different
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Another issue in measuring adoption
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Yt and we can estimate K (the maxim
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Measuring ImpactEarlier sections di
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-17The Role of Adoption Studies in
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Bo 3. Variable and Criteria __'_."C
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Farmers in Bumbogo, Rwanda grow bea
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-23The following graph shows the ac
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-25One valuable contribution to ass
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80 1A study of mechanical wheat har
Page 37 and 38: Chapter 3UnderstandingAdoptionThe F
Page 39 and 40: small test of farmers' skills (for
Page 41 and 42: Wealth. Wealthier farmers may be th
Page 43 and 44: degree of adoption may depend on th
Page 45 and 46: conditions of the preceding or foll
Page 47 and 48: equired inputs, then the technology
Page 49 and 50: help in analyzing the degree to whi
Page 51 and 52: Checklist (cont'd.).....FactorBiolo
Page 53 and 54: Box 14. Gender Analysis and Adoptio
Page 55 and 56: Box 16. Labor Availability and Adop
Page 57 and 58: 80 1 te Trade-offsFarmers must ofte
Page 59 and 60: -51The adoption of technology is in
Page 61 and 62: -53Box 22. Source of Purchased Inpu
Page 63 and 64: Box 24. Knowledge of Recommendation
Page 65 and 66: services, or markets, it is importa
Page 67 and 68: - SamplingforcomparisonsTn many ins
Page 69 and 70: chosen for the survey will determin
Page 71 and 72: B. Measurements for input use may b
Page 73 and 74: 2. Where did you acquire the seed?1
Page 75 and 76: Cha ter 5MethodsforAnalyzingAdoptio
Page 77 and 78: One of the simplest and most useful
Page 79 and 80: For instance, a survey may show tha
Page 81 and 82: -73Revised[Oxen ownership (A) --.t~
Page 83 and 84: RevisedThe association is tested co
Page 85 and 86: The following example is a simple l
Page 87: where b o is the constant, b}' b 2,
Page 91 and 92: 1Decision trees are a method of rep
Page 93 and 94: ReferencesAcharya, M., and L. Benne
Page 95 and 96: Jha, D., B. Hojjati, and 5. Vosti.
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The Adoption of Agricultural Technology - Food Security Group

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