# Measure relationship between two variables spss tutorial

2) A correlation analysis (before the regression analysis) to determine if these variables are related I have a attached a Person correlation tutorial using SPSS. Step-by-step instructions with screenshots using a relevant example to explain how to run A point-biserial correlation is used to measure the strength and direction of the Therefore, two variables were created in the Variable View of SPSS. The bivariate Pearson Correlation is commonly used to measure the The sample correlation coefficient between two variables x and y is.

Even when your data fails certain assumptions, there is often a solution to overcome this. Your two variables should be measured at the interval or ratio level i. Examples of variables that meet this criterion include revision time measured in hoursintelligence measured using IQ scoreexam performance measured from 0 toweight measured in kgand so forth.

## Pearson's Product-Moment Correlation using SPSS Statistics

You can learn more about interval and ratio variables in our Types of Variable guide. There is a linear relationship between your two variables. Whilst there are a number of ways to check whether a linear relationship exists between your two variables, we suggest creating a scatterplot using SPSS Statistics, where you can plot the one variable against the other variable, and then visually inspect the scatterplot to check for linearity.

Your scatterplot may look something like one of the following: In our enhanced guides, we show you how to: Pearson's correlation determines the degree to which a relationship is linear.

Put another way, it determines whether there is a linear component of association between two continuous variables. As such, linearity is not actually an assumption of Pearson's correlation. However, you would not normally want to pursue a Pearson's correlation to determine the strength and direction of a linear relationship when you already know the relationship between your two variables is not linear.

• Point-Biserial Correlation using SPSS Statistics

Instead, the relationship between your two variables might be better described by another statistical measure.

For this reason, it is not uncommon to view the relationship between your two variables in a scatterplot to see if running a Pearson's correlation is the best choice as a measure of association or whether another measure would be better.

There should be no significant outliers. Outliers are simply single data points within your data that do not follow the usual pattern e. This is what the Bivariate Correlations output looks like: The Descriptive Statistics section gives the mean, standard deviation, and number of observations N for each of the variables that you specified.

For example, the mean of the extravert variable is 2. The Correlations section gives the values of the specified correlation tests, in this case, Pearson's r.

SPSS for Beginners 5: Correlations

Each row of the table corresponds to one of the variables. Each column also corresponds to one of the variables.

In this example, the cell at the bottom row of the right column represents the correlation of extravert with extravert. Kind of silly, isn't it!

### Using SPSS for Correlation

This correlation must always be 1. Likewise the cell at the middle row of the middle column represents the correlation of rather stay at home with rather stay at home. It too, must always be 1. The cell at middle row and right column or equivalently, the bottom row at the middle column is more interesting. This cell represents the correlation of extravert and rather stay at home or rather stay at home with extravert -- it doesn't matter.

There are three numbers in these cells. The top number is the correlation coefficient. The correlation coefficient in this example is The middle number is the significance of this correlation; in this case, it is.