PSYCH 100A Lecture Notes - Lecture 7: Null Hypothesis, Analysis Of Variance, Scatter Plot
Document Summary
Pairwise (post hoc) comparisons: examine mean differences between all possible pairs of groups, used when researches don"t have specific hypotheses about group differences prior to study. Idea that two events tend to happen together: correlation (r )describes associations/trends between two continuous variables. Use correlation: t tests apply to situations where we want to examine relationship between categorical independent variable and continuous dependent variable, but correlation used to evaluate association between two continuous variables. Scatterplot: helps visualize a correlation, correlation differs in direction and strength. Independent on horizontal, outcome on vertical: can be positive or negative, strength of correlation ranges from weak (nonexistent) to strong (perfect) Positive correlation: high paired with high, low paired with low. Negative correlation: high paired with low, low paired with high. Pearson"s correlation: denoted r, quantifies magnitude of correlation on a 0 to 1 scale, slope of the line. Outliers (extreme scores: have substantial impact on correlation, can increase/decrease depending on location of outlier.
