Collecting Data: notes and practice questions
- This topic covers the essential skills for gathering information during a scientific investigation.
- Identify and record relevant qualitative observations.
- Collect and record sufficient relevant quantitative data.
- Identify and address issues that arise during data collection.
How it is examined
Paper 1B. Appears as reading a value off a supplied graph or table to a stated precision, and as "identify an issue with the way this data was collected". May 2025 Paper 1B TZ1 question 1(c) asked for a reading of 994 (±1) kg m⁻³ from a graph as its first marking point, which is a collecting-data mark inside an interpreting-results question.
- Identify and record relevant qualitative observations.
- Collect and record sufficient relevant quantitative data.
- Identify and address issues that arise during data collection.
Practice questions
2 questions · 2 mediumQuestion 1
MediumPaper 2 · calculator5 marksTwo students, X and Y, are measuring the period of rotation, , of a turntable using a digital stopwatch with a precision of . The turntable is set to rotate at a constant angular velocity.
Student X measures the time for one single, complete revolution. They repeat this measurement 20 times and then calculate the mean of their readings.
Student Y measures the total time taken for 20 consecutive revolutions and then divides this total time by 20 to find the period.
(a) The stopwatch is functioning correctly. State the principal source of random uncertainty in an individual time measurement.
(b) Suggest a reasonable value for the absolute uncertainty in a single time measurement.
(c) Explain which student's method will yield a more precise value for the period .
Think about the process of starting and stopping the stopwatch. What limits the precision of this action by a human operator?
What is a widely accepted approximate value for human reaction time when pressing a button?
Precision is related to random uncertainty. Compare the percentage uncertainty for a single short measurement versus one long measurement, given the same absolute uncertainty in timing.
Question 2
MediumPaper 2 · calculator10 marksA student conducts an experiment to investigate the relationship between the period of a simple pendulum and its length . The student measures the time taken for 20 complete oscillations for various lengths of the pendulum string.
(a) State:
(i) the independent variable.
(ii) the dependent variable.
(iii) one variable that should be controlled.
(b) The student uses a digital stopwatch to measure the time. They have a consistent reaction time, starting the stopwatch 0.15 s after the pendulum bob is released from its highest point. State and explain whether this is a random or a systematic error.
(c) The student measures the time for 20 oscillations rather than for a single oscillation. Suggest why this experimental technique improves the measurement of the period .
(d) For a pendulum of length 1.00 m, the accepted value for the period is 2.01 s. The student takes three measurements of the time for 20 oscillations and calculates the period for each. The results are 2.15 s, 2.16 s, and 2.14 s. Distinguish between accuracy and precision, using the student's results as an example.
Think about what the student is deliberately changing, what they are measuring as a result, and what other factors could affect the outcome that need to be kept constant.
Does this error affect each measurement randomly, or does it introduce a consistent offset in one direction?
Consider the effect of the uncertainty in starting and stopping the timer. How does measuring a longer total time interval affect the fractional uncertainty of the final calculated period?
Accuracy relates to the 'true' value, while precision relates to the consistency of repeated measurements. How do the student's results compare to the accepted value and to each other?
No question on this page matches those filters. Try another difficulty or paper.
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Where marks are lost
- Stopping one step short of the conclusion. Two numbers and no sentence is two marks out of three.
- Answering a procedure question with a platitude.
- Losing precision in Paper 1B. Uniquely to this paper, quoting the right number badly loses marks.
