W1 - Experimental Design & Inferential Stats Flashcards
Methods of controlling secondary variables include (5)
Elimination, constancy, making a second variable into an independent variable, randomisation, statistical adjustment
An example of elimination is
Using a soundproof room to eliminate external noise
An example of constancy is
Holding illumination steady in a perception experiment
Randomisation process is useful when
There are too many secondary variables to allow for. Results are based on probability.
Statistical adjustment is used when
A variable can be compensated for. Eg subtracting a pre-test from a post-test
The sources of invalidity include
Testing effects, regressing towards the mean, maturation, subject attrition, repeated measures interactions, dv measurement error, experimenter bias
-TRAMB
Generalisability is sought for
Clients, settings, experimenter-therapist discrepancies, dependent variable
Internal validity is highest when
All secondary variables are controlled
Non-parametric test data assumes
Nominal or ordainl data
Parametric test data assumes
Interval or ratio data
Parametric tests include
t-test, ANOVA
When comparing two means, null hypothesis is
pop1=pop2, or, pop1-pop2=0
When comparing 3 means, null hypothesis is
Pop1=pop2=pop3
A t-test compares how many means?
2
An ANOVA compares how many means?
3 or more