== Questions about correlations == 1. [[FAQ/skew|How should I deal with outliers when doing correlations?]] 1. [[FAQ/rankit|Rank-based and other correlations (percentage bend) which are robust to non-Normal data]] 1. [[FAQ/rt1d|How do I correlate change in score with the score at baseline?]] 1. [[FAQ/balt|How do I measure agreement to see if two measures are measuring the same thing (Bland and Altman plots)?]] 1. [[FAQ/constr|Can I do a correlation between two variables where one variable is less than or equal to the other?]] 1. [[FAQ/partsp|How do I produce nonparametric Spearman partial correlations using SPSS?]] 1. [[FAQ/Collinearity|What is Collinearity in multiple regression, and what do I do about it?]] 1. [[FAQ/WilliamsSPSS|How do I compare a pair of correlations?]] 1. [[FAQ/avcor|How do I obtain an average correlation?]] 1. [[FAQ/cronr|How do I work out reliability for three or more items? (Cronbach's alpha, composite reliability and Raykov's rho)]] 1. [[FAQ/conval | What thresholds should I use for convergent validity?]] 1. [[FAQ/corrs|How do I test if a correlation is zero and obtain its confidence interval?]] 1. [[FAQ/corrdf|How many degrees of freedom are associated with a test of whether a zero-order or multiple correlation equals zero?]] 1. [[FAQ/rdf|How do I estimate a pooled correlation using multiple scores from a set of subjects?]] 1. [[FAQ/pvs|How do I adjust p-values to test if more than one correlation is zero?]] 1. [[FAQ/corrsCi|How do I obtain a 95% confidence interval for a correlation (or slope in a simple regression) in SPSS?]] 1. [[FAQ/adjgp|How do I adjust a correlation for group differences (using partial and semi-partial correlations)?]] 1. [[FAQ/Power| Power calculations for testing if correlations equal zero]] 1. [[FAQ/polychoric| What are polychoric correlations and how do I compute them and use in SPSS?]] 1. [[FAQ/icc| What are intraclass correlations and how do I use them?]] 1. [[FAQ/multiicc | How do I compute consistency across subjects using an intraclass correlation?]] 1. [[FAQ/rest| A note on correcting for restriction of ranges which underestimate Pearson correlations]] 1. [[FAQ/RegCor|What is the relationship between significance tests of regression coefficients and of correlation coefficients?]]