Statistics, Data, and Probability II Drill 5 Problem 2. Based on this data, a student who had missed 10 days of school can expect his GPA to be about what?
|CAHSEE Math||Statistics, Data, and Probability II|
|Statistics||Charts, Graphs, and Tables|
|Statistics and Probability||Interpret linear models|
|Statistics, Data Analysis, and Probability 7||Scatterplots|
in a semester, and their semester GPAs were. The results are shown in the plot below.
Based on this, a student who had missed 10 days of school can expect his GPA to be about…what?
And here are the potential answers...
OK, so this question is testing whether we
know the difference between positive and negative correlations.
The basic idea is that if elements are positively correlated, they generally head in the same direction.
So... given NO OTHER DATA, if we just looked at this scatter plot of points, we’d surmise
that they generally drift south as we move to the right.
There is a clear ‘directionality’ to them. So we've got absences on one side and GPA on the other.
How much are they alike?
As we get higher in absences we have a LOWER grade point average – so in this case it’s
a pretty clear NEGATIVE correlation.
That is – more absences means lower grades.
If it had been more absences means HIGHER grades, we’d have the dots gradually sloping
UP instead of down… …and we’d have a whole lot fewer kids in school.
The answer is B.
As in… “Brains don’t work that way.”