Year 8 Science · Unit 4 · Lesson 12
Challenge Worksheet
Learning Goals
Read the graph
Three student groups each ran an experiment three times and measured the result in centimetres. The expected (true) value is 10 cm. Study the bar chart and answer the questions.
Data: simulated repeated measurement experiment, HSCScience Lab.
(a) Which investigation produced the most reliable results? Explain how you know using values from the graph.
(b) Investigation C gives consistent results across the three trials, but all results are far above the expected value of 10 cm. Explain why this means the data is reliable but not valid, and suggest one possible cause of the error shown in the graph.
(c) Which investigation's results would you least trust as evidence for a scientific conclusion? Justify your answer using two specific reasons.
Pharmaceutical study — evaluate the evidence
A pharmaceutical company releases results claiming their new drug reduces blood pressure. The study involved 12 patients, each taking the drug for one week. No control group (patients receiving a placebo) was included. Each patient was measured only once at the end of the week. The study was funded entirely by the company selling the drug, and the results have not been published in a peer-reviewed journal.
(a) Evaluate this study using three specific data quality criteria from this lesson (e.g. reliability, validity, sample size, bias, peer review). For each criterion: state whether the study meets it and explain why.
(b) What is the minimum standard of evidence that Australia's Therapeutic Goods Administration (TGA) should require before approving a new drug for public use? Describe at least four features the study must have.
(c) Why does the funding source of a study matter when evaluating data quality? Explain using the term confirmation bias.
Wrap Up
In one sentence, what was the main idea of this lesson?