# W7 - Regression Flashcards

What is regression analysis used for?

To predict one variable based upon the score in the other variable.

What is regression concerned with?

Prediction of 1 variable from a RELATED variable

In what 3 ways does regression + correlation analysis differ?

In its purpose

How variables are described

The inferential tests

3 ways in which regression + correlation analysis differ

What is meant by in its purpose

When talking about correlations = talk about relationships, associations + correlations.

Regression analysis = Clearly talking about prediction.

3 ways in which regression + correlation analysis differ

What is meant by how variables are described

For correlation analysis = makes no difference which variable is on X or Y axis of scatterplot.

Regression analysis = Independent always on X axis, dependent variable always on Y axis.

3 ways in which regression + correlation analysis differ

What is meant by the inferential tests

Correlation analysis = Primarily interested in the r value.

Regression analysis = Interested in 3 bits of info;

- r^2 value (shared variance between 2 variables)
- Intercept (a)
- Regression coefficient (b)

What does the regression line on a graph do?

Minimises the vertical deviations of the points from the line

What does it result in when the vertical distance between the line + points on a scatter plot are minimised?

We are minimising the error of prediction

For a scatter plot with regression analysis, what is also known as the dependent variable on the y axis?

Predicted variable

For a scatter plot with regression analysis, what is also known as the independent variable on the x axis?

Predictor variable

What is the bivariate regression equation?

Algebraic equation expressing the prediction of 1 variable by another

How is the bivariate regression equation usually written?

Y = a + bX

Also written as:

Y = bX + c

^^ Where C=a

BIVARIATE REGRESSION EQUATION

What does the Y represent?

Dependent variable

BIVARIATE REGRESSION EQUATION

What does the a represent?

Constant (Y intercept)

Where the line of best fit would cross through the y axis

BIVARIATE REGRESSION EQUATION

What does the X represent?

Independent variable

BIVARIATE REGRESSION EQUATION

What does the b represent?

Regression coefficient (slope)

= Change in y / change in x

Steps to perform regression analysis

1+2. Consider Null + Alternative hypothesis |(make sure to include WILL or will NOT predict)

- Select level of significance
- Collect + summarise data
- Check assumptions
- Run Statistical test
- Interpret significance of result

Steps to perform regression analysis

Give a null hypothesis example for:

Sum of skin fold measures + body fat %

There’s no significant relationship between the variables.

More specifically, the sum of skin folds will NOT predict % body fat.