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
