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Module 5: Scientific Investigations
Quick questions on Reliability, validity, accuracy and precision: HSC Investigating Science Module 5
12short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is validity?Show answer
The extent to which an investigation tests what it claims to test. A valid investigation:
What is reliability?Show answer
The extent to which an investigation produces consistent results when repeated. A reliable investigation:
What is accuracy?Show answer
How close a measurement is to the true or accepted value. A measurement that consistently disagrees with the true value by a fixed amount is inaccurate, even if it is precise.
What is precision?Show answer
How close repeated measurements are to each other, regardless of whether they hit the true value. Precision describes the spread of a measurement set.
What is how to improve each?Show answer
:::worked Worked example A class measures the freezing point of distilled water using digital thermometers.
What is threats to validity?Show answer
Confounding variables, sampling bias, measurement instruments that do not measure what is claimed.
What is threats to reliability?Show answer
Random error, inconsistent technique, unstable equipment.
What is threats to accuracy?Show answer
Systematic error, calibration drift, observer bias.
What is threats to precision?Show answer
Random error, low-resolution instruments, careless technique.
What is saying valid when meaning reliable?Show answer
Validity is about whether the experiment measures the right thing. Reliability is about whether it measures it consistently.
What is improving reliability by more replicates is correct?Show answer
Improving validity by more replicates is wrong. Validity is about design, not repetition.
What is ignoring the difference between random and systematic error?Show answer
Random error reduces precision but not accuracy on average. Systematic error reduces accuracy regardless of replication. :::