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Data Lab #6 July 9, 2008. Ivan Katchanovski , Ph.D. POL 242Y-Y. Correlation: SPSS Commands. SPSS Command: Analyze-Correlate- Bivariate -Pearson Research Hypothesis: The level of economic development has a positive effect on the level of democracy Dataset: World Variables:
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Data Lab #6July 9, 2008 Ivan Katchanovski, Ph.D. POL 242Y-Y
Correlation: SPSS Commands • SPSS Command: Analyze-Correlate-Bivariate-Pearson • Research Hypothesis: The level of economic development has a positive effect on the level of democracy • Dataset: World • Variables: • Freedom House democracy rating reversed: • Dependent variable • Interval-ratio • GDP per capita ($1000): • Independent variable • Interval-ratio
Example: Interpretation • Pearson Correlation Coefficient: .607 • Positive association in expected direction • Strong association • Statistical significance • SPSS: p(obtained)=.000 <p(critical)=.001=.1% • Statistically significant at the .001 or .1% level • Research hypothesis: supported by correlation analysis • The level of economic development has a positive and statistically significant effect on the level of democracy
Scatterplot: Example • SPSS commands: Graphs-Interactive-Scatterplot • Assign variables: • Vertical axis box: select the dependent variable • Freedom House democracy rating reversed • Horizontal axis box: select the independent variable • GDP per capita ($1000) • Double click to edit scatterplot • Positive association between the economic development level and the democracy level
Correlation Matrix • Correlation Matrix: correlations of more than 2 variables • Example: The Greatest Portuguese vote reliability check • Variables: TV vote, Poll 1, Poll 2 • TV vote is weakly correlated with Poll 1 and Poll 2 • Correlations of TV vote with Poll 1 and Poll 2 are statistically insignificant • Poll 1 and Poll 2 are strongly correlated • Correlation between Poll 1 and Poll 2 is statistically significant at the .05 level • TV vote data are not reliable measure of public opinion concerning “Greatest Portuguese” • Public opinion polls are reliable measure of public opinion concerning “Greatest Portuguese”
Greatest Portuguese: SPSS Correlation Matrix * Correlation is significant at the 0.05 level (2-tailed).
Correlation Matrix: Table Table 1. Correlation Matrix *** Correlation is significant at the 0.001 level.