Recording results in tables and criticising data

A good results table

• Independent variable in the first column, dependent variable next, then any processed columns (mean, T², 1/l...).
• Column headings give the quantity and unit, separated by a slash: l / m, T / s, T² / s². Units go in the heading only, not after each number.
• Columns for each repeat and for the mean.
• Raw data to the instrument's resolution, with consistent decimal places; processed data to sensible significant figures.

What to criticise

When asked to comment on an inexperienced student's results, look for:

• too few readings for a reliable graph (fewer than about six);
• a narrow range of the independent variable;
• no repeats, so no mean or uncertainty;
• inconsistent decimal places or significant figures;
• units missing or in the wrong place;
• a specific anomalous reading (name it: 'the time at 80 cm');
• values recorded beyond or short of the instrument's resolution.

An inexperienced student's table: spot the problems.

Suggesting improvements

Improvements should be specific: 'take readings at six lengths from 20 cm to 120 cm', 'repeat each timing three times', 'add a timing marker at the equilibrium position', or extra apparatus where appropriate (a set square, a clamp). Comments about the interval between values are not usually credited on their own.

Worked example

Criticise the student's table shown in the lesson.

1. Only four lengths: too few for a reliable graph.
2. Inconsistent decimal places in the times (9.0 and 12.71).
3. Units written in the period column cells rather than the heading.
4. No repeats, so no mean or uncertainty can be found.
5. The 80 cm value does not fit the pattern (the period should rise roughly as the square root of length): repeat it.

Answer: Any of these, each stated specifically

Check yourself

1. Which column heading is set out correctly?
   • T² / s²
   • T² (seconds)
   • T²
   • s² / T²
   Show answer

   T² / s². Quantity, slash, unit.

2. A student records the time for four different lengths. What is the main criticism?
   • Too many readings
   • The lengths should be in metres
   • Too few readings for a reliable graph
   • Times cannot be tabulated
   Show answer

   Too few readings for a reliable graph. Six or more values are needed to establish the trend.

3. Where should units appear in a results table?
   • In the column headings only
   • After every value
   • Only in the title
   • Nowhere, if the values are clear
   Show answer

   In the column headings only. Units in the heading, separated from the quantity by a slash; the body holds numbers only.

4. A period of 1.42 s is recorded. What value of T² should go in the processed column, in s², to 3 s.f.?
   Show answer

   2.02 s². 1.42² = 2.0164, so 2.02 s².

5. A student measures the period of a pendulum for lengths 40 cm, 42 cm, 44 cm, 46 cm, 48 cm and 50 cm. What is the main problem?
   • There are too many readings
   • The range of lengths is too narrow
   • The intervals are uneven
   • Lengths should be in mm
   Show answer

   The range of lengths is too narrow. Over such a small range the trend is hard to see and the gradient is unreliable.

6. A table of current against p.d. has the values 0.12, 0.2, 0.31, 0.405 in the current column. State what is wrong and what it should look like.
   Show answer

   The decimal places are inconsistent; every current should be recorded to the same number of decimal places (the meter's resolution), for example 0.12, 0.20, 0.31, 0.41.. Raw data from one meter should share its resolution.

7. Which comment about an anomalous result would examiners credit?
   • One value does not fit
   • The time for 80 cm is anomalous because it does not fit the pattern
   • Some results are wrong
   • The data is not very good
   Show answer

   The time for 80 cm is anomalous because it does not fit the pattern. Name the specific reading and say why it is anomalous.

Practise with instant feedback Print this lesson

Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Physics specification (XPH11/YPH11), Issue 3
• Pearson qualifications: International Advanced Levels Physics (2018)
• Pearson examiners' report: IAL Physics WPH13/01, October 2024
• Pearson examiners' report: IAL Physics WPH16/01, October 2024

Last updated 8 November 2026. Spotted a mistake? Tell us.