Means, anomalies, ranges, percentage change and percentages of a total, and naming variables.
What you will learn
- Calculate means, ranges and uncertainties
- Calculate percentage change, with its sign
- Name independent, dependent and control variables
Handling repeats
Repeat measurements, leave out anomalies (values far from the rest), then take a mean.
Half the range gives a rough uncertainty.
percentage change = (final − start) ÷ start × 100
- potato 2.50 g before, 2.30 g after
- (2.30 − 2.50) ÷ 2.50 × 100 = −8.0%
Percentage change lets you compare pieces that started with different masses. A loss is negative.
The rest of this lesson and its 9 practice questions are locked.
In this lesson
- Handling repeats
9 practice questions, marked as you go; about 20 minutes in all.
In this unit: Required practicals and maths skills
The skills behind every biology practical: units and magnification, means and percentages, rates and graphs, sampling, ratios and planning.
- Units and magnification
- Means, percentages and uncertainty
- Rates and graphs
- Sampling and estimates
- Ratios and probability
- Required practicals review
- Working scientifically