A table question about a hypothesis tests whether the numbers support every part of a prediction. Read the hypothesis and any added prediction, then list what each one needs. Use the title and column headings to find the groups and what each number measures. To measure a treatment’s benefit, compare it with the other treatment within the same setting, then compare those gains across settings. Accurate numbers can still miss the claim if they answer a different question.
Hints
- Hint 1
Read the sentences beginning “Ecologists” and “They further predicted.” List what each sentence asks the results to show.
- Hint 2
Read the canopy setting and leaf-litter treatment columns together. Look for the two treatment rows within each setting.
- Hint 3
Subtract the removed-litter value from the retained-litter value for each measured result in each canopy setting. How do those gains compare across the settings?
Step-by-step
Compare litter gains
Step 1Find every part of the hypothesis
The ecologists expect litter to improve dry-season survival by reducing soil-water loss, and predict that this benefit would be greater in open patches. What would support the whole hypothesis? We need to measure the survival and soil-moisture gains from keeping litter, then compare those gains between open and shaded plots.
- Step 2
Calculate gains within each setting
The table gives survival and soil moisture as percentages, with retained and removed litter in each canopy setting. How do we measure the litter’s benefit? Because plots were assigned either to retain or to have their leaf litter removed, subtract the removed-litter value from the retained-litter value within each setting to get a percentage-point gain, the difference between two percentages. In open plots, survival gains 57 − 34 = 23 points and moisture gains 18 − 11 = 7 points. In shaded plots, survival gains 68 − 62 = 6 points and moisture gains 24 − 22 = 2 points.
- Step 3
Test what each comparison shows
Do all the findings measure the litter benefit in both settings? The line with among retained-litter plots, average soil moisture skips the moisture gains, while the line with among retained-litter plots, survival skips the survival gains. The line with shaded plots exceeded open plots gives litter gains only for open plots. The finding with 23 versus 6 for survival and 7 versus 2 for soil moisture reports the survival and moisture gains from keeping litter, each greater in open patches. Choice C.