Week 8: Linear regression Flashcards
What kind of variables are needed for linear regression?
2 continuous
What symbol is used for the correlation coefficient?
r
What does r vary between?
-1 and +1
What two pieces of information do you get from the correlation coefficient?
The direction (positive or negative)
The magnitude
What happens in a positive relationship?
As one variable goes up, so does the other
What happens in a negative relationship?
When one variable goes up, the other decreases
The regression line helps to…
Predict other scores
What is the regression equation?
= b (X) + a
What is b in the regression equation?
The slope - how much change in the outcome for each increase in the predictor
What do you multiply b with in the regression equation?
The value of the predictor variable
What is a in the regression equation?
The intercept - value of the outcome variable when the predictor is 0
How do you set up the data for a regression analysis in jamovi?
1x row per participant
1x column for each variable
all need to be continuous
What is the independent variable called in linear regression?
Predictor variable
What is the dependent variable called in linear regression?
Response or outcome variable
How do you begin the analysis in jamovi?
Regression - linear regression
DV box: put the variable in that you want to predict the outcome of
Covariates: continuous predictors - put predictor in
What fit measures and model coefficients do you ask for in a linear regression?
r
R squared
Adjusted r squared
ANOVA
Confidence intervals
What does r give you?
The correlation between the IV and DV
What does Rsquared tell you?
The proportion of the variance for a dependent variable that’s explained by an independent variable
Adjusted R squared
like R squared but takes into account smaller sample sizes
How do you generate a scatter plot in jamovi?
Exploration - scatter plot
Predictor in X axis box
Outcome into Y axis
Which table gives you the values for the regression equation?
The Model coefficients box
Also gives you the ability to give t tests for the slope, and the intercept
Which line definitely needs to be significant in the model coefficients box?
The slope - has to be different to zero
Both should be but especially the slope
Regression becomes more reliable when….
The sample size increases
Correlation and regression differences?
Correlation gives you the strength of the relationship between two continuous variables
Regression builds a model of this relationship to allow the prediction of other scores