Repeated-Measures ANOVA
Repeated Measures ANOVA
SStotal
SSwithin treatments
SSsubjects
SSerror
Repeated Measures ANOVA
formulas:
SS total = Σx2 - (Σx)2/N
SS <strong>within treatments</strong> = n Σ(x̄w - x̄)2
SS subjects = k Σ(x̄s - x̄)2
SS error = SStotal - SSwithin treatments - SSsubjects
Repeated Measures Anova
MStreatment
dftreatment = k - 1
MSerror
dferror = (k-1)(n-1)
When calculating SSerror, eliminates effects of MSsubjects
Repeated Measures Anova
1) Normality
2) Sphericity
Repeated Measures ANOVA ASSUMPTIONS
2) Sphericity
assumption of equal variances & equal covariances
(NOT robust to violations)
Factorial ANOVA
2 b/w-subject IVs of 2 levels
Main effect
mean difference among levels of one factor
Interaction
mean differences between treatment conditions (cells) are different from what would be predicted from overall main effects of factors
Two-Factor ANOVA
(3) hypothesis tests?
1) main effect of A
2) main effect of B
3) A x B interaction
Two-Factor ANOVA
SS total
SS BG
SS WG
SS A
SS B
SS AxB
Two Factor ANOVA
Formulas:
SS total = ΣXtotal2 - ( ΣXtotal)2/N
SS BG = ΣT2/n - G2/N
SS WG = SST - SSBG
SS A = ΣTrow2/nrow - G2/N
SS B = ΣTcolumn2/ncolumn - G2/N
SS AxB = SSBG - SSA -SSB
Two-Factor ANOVA
MS for:
F = MS/MSWG
Correlation
describes linear relationship between 2 ordinal/interval level variables
Correlation
1) linear
2) magnitude of correlation coefficient
Correlation
1) Normality
2) Linearity
3) Homoscedasticity
Correlation ASSUMPTIONS
3) Homoscedasticity
assumes variance around regression line is same for all X values
(equal spread)
Regression
technique to fine line of best fit
Correlation suggests we can….
predict Y values for given values of X
If correlation is perfect, all points will..
If NOT?
Regression
Notation for:
1) Y’
2) Y-Y’
3) b1
4) bo
Regression
errors of underprediction & overprediction
Sum of squared residuals is?
Minimal
(regression line = best-fitting line)
Regression
Y’ = b1x + bo