== FAQs for analysis of variance ==
1. [[FAQ/Sattherthwaite|Why are the degrees of freedom not whole numbers?]]
1. [[FAQ/ttestEXC|How do I compare a mean to a constant in EXCEL (one-sample t)?]]
1. [[FAQ/ciplots|How do I calculate a 95% confidence interval for the group means from one-way ANOVAs (using either a within or between subjects factor)?]]
1. [[FAQ/ttst|How do I compute a t-test and F ratio using only summary measures in 2x2 between and within subjects ANOVA?]]
1. [[FAQ/Solomon| A two-way analysis of variance to assess treatment and pre-test effects (Solomon's four group design)]]
1. [[FAQ/df|How do I work out degrees of freedom for terms in an ANOVA?]]
1. [[FAQ/E|What does a number containing an 'E' signify and how do I remove it?]]
1. [[FAQ/SumsOfSquaresTypes|In ANOVA and Regression, what do the various different types of Sums of Squares mean, and does the choice matter?]]
1. [[FAQ/subsrandom|Can I use subjects as a random or fixed factor in an ANOVA?]]
1. [[FAQ/Rss|Sums of squares used by R in lm, lmer and aov]]
1. [[FAQ/wmeans|A note about unequal group sizes in ANOVA]]
1. [[FAQ/sstypes|A note about different sums of squares in unbalanced factorial ANOVAs]]
1. [[FAQ/FVars| What is the variance of the mean of my transformed data?]]
1. [[FAQ/VarMSE| What is the value of the error variance for raw data using that of its scalar transformed data?]]
1. [[FAQ/rmform| How do I format data for input into a repeated measures analysis in SPSS?]]
1. [[FAQ/transp| What does the TRANSPOSE ALL DATA option in the RESTRUCTURE menu do in SPSS?]]
1. [[FAQ/restwb| Using the VARSTOCASES command in SPSS to convert repeated measures formatted data to a multilevel model format (and the CASESTOVARS command for the reverse operation).]]
1. [[FAQ/glmrm| How do I perform a repeated measures analysis of variance in SPSS?]]
1. [[FAQ/glm99rm| How do I perform a repeated measures analysis of variance in SPSS involving repeated measures factors with more than 99 levels?]]
1. [[FAQ/anovaR| How do I perform a repeated measures analysis of variance in R including correcting for sphericity?]]
1. [[FAQ/aovgens| How do I perform a repeated measures analysis of variance in GENSTAT (and MATLAB)?]]
1. [[FAQ/aovmtb| How do I perform a repeated measures analysis of variance in MINITAB (and use this approach to obtain post-hoc tests on a repeated measures factor in SPSS)?]]
1. [[FAQ/rpcon| How do I perform a non-standard comparison of means in a repeated measures anova in SPSS?]]
1. [[FAQ/bwss| What is the effect of dropping a between by within subjects interaction on other terms in a mixed anova?]]
1. [[FAQ/Interaction|How do I work out the meaning of a significant interaction?]]
1. [[FAQ/Int4|How do I interpret a four-way interaction?]]
1. [[http://www.theanalysisfactor.com/assumptions-of-ancova/ | Why don't I need to use a covariate which differs between randomised groups in an ANCOVA?]]
1. [[FAQ/ancrm|Comparing ANCOVA to Repeated Measures ANOVA]]
1. [[FAQ/ancreg|Can I do an analysis of covariance using a regression (including computation of covariate adjusted means) and use this to adjust for regression to the mean?]]
1. [[FAQ/ANORES|ANCOVA versus Analysis of Residuals]]
1. [[FAQ/errsvars|How do I handle errors in variables to estimate slopes and intercepts in a linear regression?]]
1. [[FAQ/constantcov|Inappropriate use of a constant covariate in repeated measures ANCOVA]]
1. [[FAQ/Manova|How do I adjust for varying covariates in a repeated measures ANOVA in SPSS?]]
1. [[FAQ/Manzeroes|How do I obtain an interaction in SPSS to describe how a fixed covariate influences a repeated measures interaction?]]
1. [[FAQ/WsubEffects| What is the difference between within subjects effects and within subjects contrasts in SPSS?]]
1. [[FAQ/Auc| What summary measures can I use to describe repeated measures?]]
1. [[FAQ/polybs| How do I test for a trend, or contrast, between group means in a one-way ANOVA representing different subjects and also check location of asymptotes on a curve?]]
1. [[FAQ/Tukey| How do I interpret subsets in Tukey's HSD output?]]
1. [[FAQ/TukeyKramer| How do I compare all pairwise comparisons in a between subjects anova (and in a repeated measures anova)?]]
1. [[FAQ/SimpleMainEffects|Why won't SPSS let me do post hoc tests involving a within-subjects factor?]]
1. [[FAQ/SimpleEffs|How do I do a simple effects analysis in SPSS?]]
1. [[FAQ/pvs|How do I adjust p-values for number of comparisons using SPSS, R or in a spreadsheet?]]
1. [[FAQ/SpssBonferroni|Adjusted p-values]]
1. [[FAQ/RepeatedMeasuer|Repeated measures, Mixed models and Split-plot designs: A Rant]]
1. [[FAQ/ResidsRepMeas|How do I check Normality assumptions in repeated measures analyses in SPSS?]]
1. [[FAQ/Mauchly|What is the formula for Mauchly's W used for testing sphericity in univariate repeated measures anova?]]
1. [[FAQ/orthopolys|Fitting linear orthogonal polynomials]]
1. [[FAQ/lincon|How do I compare group means in a non-standard post-hoc contrast?]]
1. [[FAQ/Dunnett|How do I compare a set of group means with a control group mean?]]
1. [[FAQ/intsg|How do I manually compute t-statistics to compare means in a repeated measures ANOVA having 3 or more groups?]]
1. [[FAQ/ss|Formulae for interaction sums of squares in balanced designs]]