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The Adoption of Agricultural Technology - Food Security Group

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One <strong>of</strong> the simplest and most useful ways <strong>of</strong> examining differences inadoption patterns is with contingency tables, in which the cells or the tablecompare the proportion <strong>of</strong> adopters and non-adopters with a particularcharacteristic. This is particularly appropriate if the characteristic <strong>of</strong> interestis a nominal one, that is, one that is represented by non-numericalcategories, such as access to irrigation (yes or no) or previous crop in therotation (potatoes, barley, or other). Even in cases where the variable is acontinuous one (such as farm size or number or days between land preparationand planting), it is sometimes useful to divide it into a few simplecategories (large vs. small; low, medium, high) and develop contingencytables. <strong>The</strong> relevant statistical test or this association is the chi-square test.In the example below, the adoption <strong>of</strong> row planting for maize is examinedin light or land preparation practices. It can be seen that there is a strongassociation. Farmers who use a tractor for land preparation are much morelikely to adopt row planting; 84% <strong>of</strong> these farmers adopt row planting,while only 29% <strong>of</strong> the farmers using manual land preparation adopt rowplanting. <strong>The</strong> chi-square test shows that it is improbable that thisassociation could occur by chance.Planting method by land preparation-- - - ~ ­.,. ­- "', ~ ',' - .!........~ '., . -'.' ,:.•• • • I !!=. ..:.- -.....:..~ •• '. ">--",_ .. ~Random 177 22 199(71%) (16%)Row 71 114 185(29%) (84%)Total 248 136 384(100%) (100%)X'?- =105.0 d.t. = 1 P < .0001<strong>The</strong> contingency table does not tell us why these two factors are related,however. It could be that tractor preparation makes row planting easier; inthis case tractor preparation is a cause <strong>of</strong> row planting. It is possible(although unlikely) that row planting "causes" tractor use, in the sense thata farmer who decides to row plant will rent a tractor for land preparation.<strong>The</strong> point is that we must go beyond presentation <strong>of</strong> the association andseek an explanation.69

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