Multiple Regression Flashcards
What are the aims of a multiple regression? (2)
a) Determine overall fit of a model
b) Establish relative contributions of the predictor variables
What is the MR equation?
Y = a + b1 x1 + b2 x2
In the MR equation (Y = a + b1 x1 + b2 x2 etc), what do a and b represent?
A = intercept B = slope
The variance in Y is explained by…(2)
- The IV
2. Residual error variance
An MR assumes that IVs are ______ and ______ _______related to IV
Collectively
Independently
Linearly
4 assumptions of a multiple regression?
1) Linear relationship
2) Homoscedasticity
3) Normal distribution
4) Large sample size
What values do we look at to determine HOW WELL THE MODEL FITS?
F
Df
P
R2
The R2 tells us
The proportion of variance in the DV explained by the IVs
“The proportion of variance in the DV explained by the IVs” What in the SPSS output tells us this?
R2
The regression equation (SPSS output)…
F = (df), p =, R2
What do the B values tell us in the coefficients table?
Change in the DV for every one unit of change in the IV
“Change in the DV for every one unit of change in the IV” - what tells us this?
B weights
B weights may either be positive or negative to indicate…
The direction of change
Which values do we look at in the coefficients table?
B Value,
Significance
What should the table of coefficients include?
B, SEb & Beta
Which 4 factors might we look at to determine the models overall fit?
- Multiple Correlation Coefficient
- Significance of overall model
- Percentage variance explained
- Precisions of predictions from model
What are the three entry options of an MR?
Direct
Hierarchical
Stepwise
Which entry option involves simultaneous entry?
Direct entry
Which entry option involves a user-determined-order entry?
Hierarchical
Hierarchical entry is usually based on…
Theory
Hierarchical Entry
After IVs are added, the increase in…
R2 is examined
Which entry option involves an SPSS-determined order?
Stepwise
Which entry option comes with the most limitations?
Stepwise
Direct Entry
How can we see the independent contributions?
Standardised beta and significance
2 Limitations of Step-wise entry?
(i) May capitalise on chance relationships
(ii) An important predictor may be excluded due to its correlation with another variable
Describe Hierarchical Entry
User-determined order based on theory
Describe step-wise entry
Discarded step-by-step according to statistical criteria
Highest correlating variable entered first
Step-wise entry
Which variable is entered first?
Highest-correlating variable
You would use the entry to assess the effect of one group of predictors over and above that of another
Hierarchical
Hierarchical entry
Who determines the order of entry?
Researcher
In all 3 types of MR, both ________ statistics and ________ statistics should be reported
Strength
Significance
Gender is a ____________ variable
Dichotomous
For HIERARCHICAL REGRESSION, when reporting the R2 CHANGE, do you report the F value from the ANOVA table?
No - model summary table
