ACTA SCIENTIARUM POLONORUM - SGGW

48 E. Majewski, P. Sulewski, M. Raggi, D. Viaggiscenarios. The test is a non-parametric method applied to nominal data and allows toexamine the significance of changes that might be influenced by specific factors. Inthe research, the factor was the hypothetical change of the CAP from Baseline to NoCAP Scenario. More specifically, the test examined whether the change of the CAPscenario had a significant influence on the number of farmers declaring “an increase” inspecific questions. For each question the results from the survey were presented in 2x2contingency tables according to the scheme below (Table 1). The mark “+” was usedto describe positive answers (e.g. continuation of farming, an increase of scale production,an increase of UAA etc.), whereas “–” to describe other categories of answers.The letter “B” in the table symbolizes the number of farmers who changed their answerfrom positive to negative in reaction to presented CAP Scenario from Baseline to NoCAP and the letter “C” symbolizes those respondents who have switched from negativeto positive answer in reaction to the change of the CAP scenario. Letters “A” and “D”indicate persons who have chosen the same category of answer in both scenarios. Thenull hypotheses stated that in reaction to changing CAP Scenario there was no significantchange in frequency of farmers pointing out positive answers “+” in comparison toalternative hypotheses stating that the frequencies were changed. No evidence to rejectnull hypothesis would mean that there is no significant influence of the presented CAPScenario on future farmers’ decisions in specific issues. To verify the null hypothesis,the following statistics was used:2 (| B−C| −1)χB+C2Under the null hypothesis, χ 2 statistics has a chi-squared distribution with 1 degreeof freedom. If calculated value Ch 2 (χ 2 ) is larger than Ch 2 under assumed alpha = 0.01,the null hypothesis should be rejected; this can be interpreted as a significant influence ofCAP Scenario on farmers declarations about their future decision.Differences between responses of farmers from 11 European regions were comparedbetween each other with the use of graphic method. Significance of differences in repliesbetween Baseline and No CAP Scenario was confirmed then with an application of statisticaltests.Table 1. Scheme of McNemar testTabela 1. Schemat testu Mc NemaraNo CAP Scenario (after changes)„+” „–‘’„+” A B A+BBaseline Scenario (before changes)„–„ C D C+DSum A+C B+D NSource:Źródło:Authors’ scheme.Opracowanie własne.SumActa Sci. Pol.