A graph question about an experiment tests whether you can use its numbers to support a claim. Start with the claim, and ask which groups it compares and what difference it needs. Then read the title, axes, and key to learn what each line measures. To measure an effect, compare groups with and without the tested change in groups that are alike in other ways, and check the size and direction of each difference. A choice can be true without showing the claim.
Hints
- Hint 1
Look at who the claim uses for comparison. For each experience level, which employees should be compared with the employees who saw the banner?
- Hint 2
Use the key to pair the lines within each experience group. How far apart are the banner and no-banner lines by Week 6?
- Hint 3
Subtract each banner rate from its matching no-banner rate, then compare the two results. How different are the reductions?
Step-by-step
Compare the banner’s effect within each group
Step 1Identify the matching groups
The researchers say the banner’s effect differed by employee experience, so we need to see how the banner changes clicking in each group. What does compared with employees who did not see the banner tell us? We compare each banner group with no-banner employees of the same experience level.
- Step 2
Find each banner versus no-banner gap
The graph tracks the percentage of employees in each group who clicked the link across six weeks. Its key pairs circles with squares for novices and triangles with diamonds for experienced employees, with solid lines for no banner and dashed lines for banner. How large are the paired gaps in Week 6? Novices have about 53% clicking without the banner versus 20% with it, and experienced employees have about 22% versus 15%. Subtraction gives 33 percentage points for novices and 7 for experienced employees.
- Step 3
Compare the size and direction
Are the banner’s effects about the same, slightly different, or very different? A 33-point gap is nearly five times a 7-point gap, so about the same amount and only slightly more don't fit. The larger gap belongs to novices, which rules out much more for experienced employees. The option saying much more for novice employees matches both the direction and the size of the gaps. Choice B.