Question

Wainer (1997) presented data on the relationship between hours of TV watching and mean score on the 1990 National Assessment of Educational Progress (NAEP) for eighth-grade mathematics assessment. The data follow, separated for boys and girls.

1. Plot the relationship between Hours Watched and NAEP math scores separately for boys and girls.
2. Find and interpret the slope and intercept for these data, again keeping boys and girls separate.

HoursTV	Girls	BOYS
0	258	276
1	269	273
2	267	292
3	261	269
4	259	266
5	253	259
6	239	249

Answer 1

We can plot the scatter plot with regression line and r² value using excel.

let us first draw for girls score and hours

First select the both data set , go to Insert ---> Charts ---> Scatter

The scatter plot will be appeared , then click on any point on the plot , right click , select add "Trendline" option

Then check the box for "Display Equation on chart " and "Display R-squared value on chart "  

Scatter plot for hours vs girls score

From the scatter plot , we can say that there is strong negative correlation exists between the both variables hours and girls scores.

Regression equation : Girls score = -3.4643*hours + 268.39

Interpretation of slope :

As hours of TV watching is increases by 1 hour , we expect to decrease in girls NAEP math scores by 3.4643

Interpretation of Intercept :

If girls do not watch the TV,,then we expect the NAEP math score of a girl is 268.39

Scatter plot for hours vs boys score

From the scatter plot , we can say that there is strong negative correlation exists between the both variables hours and boys scores.

Regression equation : Boys score = -4.8214*hours + 283.61

Interpretation of slope :

As hours of TV watching is increases by 1 hour , we expect to decrease in boys NAEP math scores by 4.8214

Interpretation of Intercept :

If boys do not watch the TV,,then we expect the NAEP math score of a boy is 283.61