Year 8 Science · Unit 4 · Lesson 7

Identifying and Handling Outliers

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Learning Goals

Apply a systematic process for investigating and handling a suspected outlier.
Decide whether it is acceptable to exclude a data point from an average, and state the conditions required.
Use correct scientific language when discussing anomalous results (outlier, anomalous, asterisk, justification).

Warm Up

Order the steps

Number the steps from 1 to 8 to show the correct order for handling a suspected outlier. Step 1 = what you do first.

Order	Step
	Decide whether to exclude the result from the average — only with written justification.
	Notice an unusual data point when reviewing your results table.
	Acknowledge the anomalous result in your discussion section.
	Attempt to repeat the measurement for that condition.
	Check instrument calibration and recalculate the value to rule out recording error.
	Compare the suspect reading to the other trials to see how far it deviates.
	If confirmed unusual, mark the result with an asterisk (*) in the data table.
	Report the full dataset including the anomalous result in your results table.

Your Turn

Scenario

A Year 8 student is investigating how temperature affects the time for sugar to dissolve. They record the following results: 20°C → 85 s, 30°C → 62 s, 40°C → 41 s, 50°C → 24 s, 60°C → 38 s. All other trials show dissolving time decreasing steadily as temperature rises — but at 60°C the time unexpectedly increases to 38 s.

(a) What makes the 60°C result a suspected outlier? Describe what you notice about the data.

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(b) What steps should the student take before making any decision about what to do with the 60°C result?

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(c) Is it ever acceptable to exclude the 60°C result from the average? If yes, describe the exact conditions that would make this acceptable.

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Wrap Up

In one sentence, what was the main idea of this lesson?