An inference question about a study tests what a comparison between groups can show. Start with the conclusion leading into the blank, then name each group and what it showed. With people assigned to groups by chance, ask what researchers changed and what stayed the same. A cause shared by both groups can't explain a difference between them, so predict only what the results support. Wrong choices often add a cause the study never tested.
Hints
- Hint 1
Read the sentences explaining how participants were assigned and how they served themselves. Name the two groups and what was kept the same.
- Hint 2
What does the difference in amounts taken tell you about the feature that changed between the groups?
Step-by-step
Compare what changed and what was shared
Step 1Name the two groups
Participants received either a light green plate or a dark green plate, so those are our two groups. What does the blank ask us to explain? The words may be affected by ask for a possible cause of how much salad people take, not a claim that must hold for every person.
- Step 2
Check what was kept alike
How did the researchers make the comparison fair? Participants were randomly assigned, meaning chance decided which plate they received. This helps keep people with different tastes spread across the groups. Both groups also served themselves from identical bowls of salad, so they had the same salad, which can't explain why one group took more.
- Step 3
Use the difference to finish
People using light green plates took 20% more salad on average than those using dark green plates. Which difference between the groups could explain that gap? The gap supports a possible effect of plate color, so the color of the plate used completes the conclusion. Choice C.