CAIE A-Level Biology A2 P5.3 Assessing Result Quality Validity and Risk Questions

Use the evidence to judge whether sample groups are large and comparable enough to reveal anomalies and support representative, valid and accurate results.

Exam points

Judge sample-size quality by checking whether groups are large and comparable, whether anomalies can be detected and whether the data are representative, valid and accurate.

[Maximum number: 2]

Researchers measured insect biodiversity on Acacia trees in the African savannah using the following method:
- insecticide was sprayed into each tree
- this killed the insects, which fell onto a sheet below the tree
- the dead insects were collected, identified and counted.

Table 5.1 shows summary statistics for some of the trees sampled in this study. The leaf canopy area is a measure of the size of the tree and the extent of its leaf cover.

Table 5.2 shows the diversity and abundance of some different taxonomic groups of insects in the study.

Table 5.1

Table 5.2

Comment on the effects of sample size on the quality and accuracy of the data in Table 5.1.

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CAIE A-Level Biology A2 P5.3 Assessing Result Quality Validity and Risk Questions question 1