Reliability and validity of health information: WACE Year 12 Health Studies Unit 4

What this dot point is asking

WACE expects you to evaluate, not just define. A strong answer applies reliability and validity to the actual source in the stimulus, checks the credibility markers, identifies a weakness, and states how much trust the information deserves. Marks reward applied judgement with reasons, not a textbook definition.

Reliability and validity

Reliability is consistency. A reliable method or measure produces similar results when repeated under the same conditions, by different people or at different times. If a survey gives wildly different results each time it is run with no real change in the population, it is unreliable.

Validity is accuracy of meaning. A valid method actually measures what it sets out to measure. A questionnaire that claims to measure physical activity but only asks about gym membership is not valid, because many active people never visit a gym.

The two are distinct and you need both. Information can be reliable but not valid (consistently measuring the wrong thing) or valid but unreliable (measuring the right thing inconsistently). Only information that is both can be trusted to support a decision.

Judging the credibility of a source

Beyond the data itself, the source matters. Useful questions include who produced the information and what expertise they have, why it was produced and whether there is a commercial or political interest that could bias it, when it was published and whether it is current, and whether the claims are supported by evidence or reviewed by others. A government health body or peer-reviewed study generally carries more weight than an advertisement, a personal blog or a brand promoting its own product, because the latter have a motive to persuade rather than inform.

Common weaknesses to look for

Several specific weaknesses reduce trust. Bias is any influence that skews the information toward a particular conclusion, including funding by a party that benefits. Sampling problems, such as a small, unrepresentative or self-selected sample, mean the findings may not generalise to the wider population. Currency matters because health knowledge changes, so out-of-date information may have been superseded. Confusing correlation with causation, or overstating a result beyond what the data support, are common errors in how findings are reported. Strong evaluation names the specific weakness rather than vaguely calling a source unreliable.

From evaluation to action

The purpose of this skill is safer decisions. Information that passes the tests of reliability, validity and credible sourcing can support a confident health decision or recommendation. Information that fails should be treated with caution or set aside, and a critical consumer seeks a better source rather than acting on weak evidence. This is the appraisal element of critical health literacy applied in practice, and it underpins the inquiry process and consumer health.

How this maps to the exam

Expect a stimulus presenting a source, study or dataset, sometimes with a flaw built in. You may be asked to evaluate its reliability, validity or credibility. Apply the tests to that specific source, name the weakness, and state how much the information should be trusted and why.