ExpertEasy1 markMultiple Choice
AQA GCSE · Question 03.3 · Bioenergetics
How could the scientist have improved the validity of the results?
How could the scientist have improved the validity of the results?
Answer options:
A.
Repeat each reading three times and calculate a mean.
B.
Use concentrations of carbon dioxide above 0.12%.
C.
Use different tomato plants for each concentration.
How to approach this question
Consider the definitions of validity, reliability, and accuracy. Validity refers to how well the experiment measures what it is supposed to measure (a fair test). Reliability is about consistency and repeatability. Which of these options would make the results more trustworthy by accounting for random errors?
Full Answer
A.Repeat each reading three times and calculate a mean.✓ Correct
Repeat each reading three times and calculate a mean.
**Validity** is about ensuring you are measuring what you intend to measure and that the test is fair. Using different plants for each concentration would make it an unfair test.
**Reliability** is about the consistency of results. By repeating each reading multiple times (e.g., three times) and calculating a mean, a scientist can spot and discard anomalous results (outliers). This makes the average result more reliable and a better estimate of the true value, which in turn improves the overall validity of the conclusion drawn from the data.
Common mistakes
✗ Confusing validity with extending the range of the investigation.\n✗ Suggesting a change that would make the test less fair, like using different plants.
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