W8: RQ for Group Differences 3 Flashcards
What is an alternative name of a dependent group
“WIthin-Subject”/ “Repeated-measures”
When is dependent group usually used
Either same people: (a) repeated occasion; (b) different condition; or matched group.
If a participants drops out of a dependent group study, how?
Sample is invalid
What do we use for preliminary analysis in a Dependent group RQ
Frequency count? and QQ Plot
Does regression apply to dependent groups
No. “independence of observation” is violated in the regression assumption
What is the difference in the univariate and multivariate approach. Which is better?
Univariate assumes sphericity; Multivariate does not. If sphericity is met, univariate > multivariate
What is the similarity between univariate and multivariate
Both assume independence of observation (which violated) and normality
What is sphericity
Homogeneity of variance of all possible DIFFERENCE (not observed) scores between pairs of levels
What is compound symmetry
Covariance martix with: (a) same variance in each diagnoal; (b) same variance in each off-diagonal
How does compound symmetry related to sphericity
Compound symmetry is a sufficient, not necessary, condition for sphericity
What does sphericity apply to? Sample or Population
Both
What is the calculation of sphericity
ε (episolon)
what is ε in terms of population/sample
Population parameter on population covariance matrix
Sample statistic on sample covariance matrix
what is the range of ε
1/k (lack sphercitiy) <= ε = 1 (perfect sphericity)
What are the 2 ε estimators
1) Greenhouse-geisser estimator (Conservative) ε_ hat
2) Huynh-Feldt estimator ε wave
In investigation of dependent group, what do we look for first
Look for Pillai. If p
What are focused linear contrast in the context of >2 dependent groups
Orthogonal polynomial contrasts: decomposition of observed change over time into constituent component rates of change
How many orthogonal polynomial contrast are there in 5 groups
K-1. 5 Groups = 4 Polynomial Contrasts
What do we look at to investigate polynomial contrast
Look for pillai. If p
is the initial investigation in R uni or multivariate . What does it mean
Multivariate. Confidence intervals might be affect if sphericity is not fulfilled.
Under what variate can interval estimators for dependent groups be calculated
Univariate approach.
What do we look at in confidence intervals in dependent groups
Look at crossing of zero
