 # Correlations. Review of Analyses n Chi-Squared –2 Qualitative Variables –Research Question: Are these variables related (Are the frequencies even) –Questions.

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Correlations

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)

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

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)

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.

Picture of Correlation Negative CorrelationPositive Correlation Correlation does not imply causation

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)

Example n Is there a correlation between a person’s sense of community and the friends they’ve met through the computer?

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.

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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