Final Exam Flashcards
What is association?
There must first be a relationship or an association between the IV and the DV
Between-subjects design:
Each set of scores is obtained from different groups of participants
Within-subjects design:
Different sets of scores are obtained from the same group of participants
Characteristics of between-subjects design:
- Experimental research wherein a researcher manipulates an IV ► then measures the DV for each participant
- Goal: determine whether differences exist between two or more treatment conditions
Disadvantage of between-subjects design:
- large # of participants
- scores from each person is unique & may produce high variability in scores
What are the 2 major sources of confounding variables in between-subjects?
- confounding from ind. differences (assign. bias)
2. confounding from env. variables
What is a confounding variable?
any extraneous variable systematically differentiating the groups (ex: age)
What are the 3 techniques to limit confounding variables?
- random assignment
- matching groups
- holding variables constant
Large differences between treatments are good because…
they provide evidence of differential treatment effects
Large differences within treatments are bad because…
differences that exist inside the treatment conditions determine the variance of the scores (large variance can hide patterns in the data)
What is a factor?
The independent (or quasi-independent) variable that designates the groups being compared
What are levels?
Individual conditions or values that make up a factor
What is a factorial design?
A study that combines two or more factors
Alt Hypothesis H1:
There is at least one mean difference among the populations
Is between-treatments variance the numerator or denominator of the F-ratio?
numerator
Is within-treatments variance the numerator or denominator for the f-ratio?
denominator
F ratio formula:
differences including any treatment effects/differences with no treatment effects
If the null hypothesis is true….
then the value of F will be close to 1.00
What are the assumptions of a ANOVA?
- The observations within each sample must be independent.
- The population from which the samples are selected must be normal.
- The populations from which the samples are selected must have equal variances(homogeneity of variance).
- Violating the assumption of homogeneity of variance risks invalid test results.
What is a partial correlation?
A partial correlation measures the relationship between two variables while mathematically controlling the influence of a third variable by holding it constant
Pearson’s correlation uses:
data from interval or ratio measurement scales
Spearman (Rs) uses:
ranking (ordinal scale)
Point-biserial correlation:
One variable has only two values(called a dichotomous or binomial variable)
R2 (squared):
- measure of effect size
- amount of variance accounted for
Phi coefficient:
- Both variables are re-coded to values 0 and 1 (or any two digits)
- Both variables (X and Y) are dichotomous
Regression analysis
precisely defines the line.
General equation for a line:
Y = bX + a
Regression:
a line that is the best fit for the actual data that minimizes prediction errors.
What is latin squared?
a way to counterbalance
Beta coefficients in multiple linear regression
The higher the beta value the greater the impact of the predictor variable on the criterion variable
Mediator variables:
A mediation model is one that seeks to identify and explain the mechanism or process that underlies an observed relationship between a predictor variable and the criterion variable via the inclusion of the third hypothetical variable, that is, a mediator variable.
ex: iq –> study habits –> exam scores
Moderator variables:
Amoderator variable is a thirdvariablethat affects the strength of the relationship between a predictor variableand a criterion variable in regression analysis
Parametric tests share several assumptions:
- Normal distribution in the population
- Homogeneity of variance in the population
- Numerical score for each individual
Nonparametric tests are needed if…
if research situation does not meet all these assumptions.
For Chi-square &nonparametric tests:
do not state hypothesis in terms of a population parameter
Categorizing makes what?
nonparametric
Choice of statistical procedure determined primarily by the…
the level of measurement.