The slope of the regression line is approximately 0.5. This means that for every 1 unit increase in the child's score, the adult's IQ increases by 0.5 units.
Eyeball-estimating the regression line
To eyeball-estimate the regression line, we can draw a straight line that passes through the middle of the scatterplot.
We want the line to be as close to as many points as possible, but we don't have to worry about it passing through any specific points.
In the scatterplot provided, the points are generally trending upwards from left to right.
This means that the regression line should have a positive slope.
We can also see that the points are not tightly clustered together, but they are not completely scattered either.
This suggests that the regression line should have a moderate slope.
Here is an eyeball-estimated regression line for your scatterplot:
Determining the slope of the regression line
The slope of a line is calculated as the change in y divided by the change in x.
In the context of a scatterplot, the slope of the regression line tells us how much the adult's IQ changes for every 1 unit increase in the child's score.
To estimate the slope of the regression line, we can choose two points on the line and calculate the slope between them.
For example, we can choose the points (10, 85) and (40, 115).
The slope of the line between these two points is:
(115 - 85) / (40 - 10) = 0.5
Therefore, we can estimate that the slope of the regression line is approximately 0.5.