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Correlations
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Review of Analyses n Chi-Squared –2 Qualitative Variables –Research Question: Are these variables related (Are the frequencies even) –Questions to Ask n Is there a significant relationship? (chi-squared, df, p) n How strong is the relationship? (phi) n Where is the relationship (std resid)
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More Review n T-tests and ANOVAs –1 Qualitative and 1 Quantitative Variable –Research Question: Are the means different for the different groups? –2 groups: Use a t-test –>2 groups: Use ANOVA
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Still More Review n T-tests and ANOVAs –Research Questions: n Is there a significant difference? (T-test: t-test statistic, df, p; ANOVA: F, df, p) n Where is the relationship? (means, std deviations, ANOVA also looks at Tukey)
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Correlations n What is a correlation? –Tells the direction of the relationship between variables. –Are correlated if as one variable increases, the other variable increases, too –Or if as one variable increases, the other variable decreases.
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Picture of Correlation Negative CorrelationPositive Correlation Correlation does not imply causation
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Correlations n Bivariate Correlation n Questions to ask: –Is the correlation statistically significant? (Pearson r, p value, N) –What direction is the correlation? (Positive or negative?) –How strong is the correlation? (closer to 1 or -1 is stronger. Close to 0 is weak)
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Example n Is there a correlation between a person’s sense of community and the friends they’ve met through the computer?
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Example Continued n Is there a significant correlation? – r=.32, p<.001 So Yes! It is significant n What direction is the correlation? Positive n How strong is the correlation? –correlation is.32 which is closer to 0 than to 1. I’d say it’s a moderate relationship.
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Example Continued n Interpretation in English: –A person’s sense of community (SOC) is positively related to the number of friends a person says he or she has met through the computer. That is, the greater someone’s SOC with a computer group, the more friends they report to have met through the computer. This relationship is moderate in strength.
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