Interval/ratio measures of association

what is a scatterplot?

it’s a visual representation of how changes in one variable affect changes in the other

1) title: type of graph of dependent by independent

2) label axes using the variable labels

3) plot the values of the iv (plotted on x axis) and dv (plotted on y axis)

4) each ordered pair is represented as a point on the graph showing the relationship between the two variables and if 2 have the same point just put 2 in brackets above it

5) determine the relationship - negative or positive

what is pearson’s r?

asymmetrical measure, used to determine strength, direction, and co-efficient of determination

co-efficient of determination: the percentage in variation (change) in the dv that is explained by the iv

what are the steps for pearson’s r?

1) determine x and y

2) create a frequency table with x, y, xy, x² and y²

3) make a little table with the sums of everything

use the formula

and square it → r² = the answer squared

the finding is: x% of the differences found in the dv is explained by the iv

x