Tabulating Data
A results table places the manipulated variable in the first column and the responding variable in the following columns, with each column heading stating the quantity and its unit, and values recorded to a consistent number of decimal places.
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Rules for drawing a table
- The manipulated (independent) variable is placed in the leftmost column, listed in a logical order, usually increasing.
- The responding (dependent) variable, and any repeated readings or averages, are placed in the columns to the right.
- Every column heading must state the quantity being recorded and its unit, written in brackets, such as 'Temperature (°C)' or 'Volume of gas (cm3)'.
- Values in each column should be recorded to a consistent number of decimal places, matching the precision of the measuring instrument used.
- A ruler is used to draw a table with clear horizontal and vertical lines, and the table should have a suitable title if required.
Handling repeats and averages
When an experiment is repeated to improve reliability, each trial should have its own column, followed by a final column for the average (mean) value. If one reading in a set of repeats is clearly anomalous, it should be identified and excluded from the average, with the reason noted.
Worked example structure
| Concentration of enzyme (%) | Time taken (s) | Rate of reaction (1/s) |
|---|---|---|
| 0 | 120.0 | 0.0083 |
| 5 | 60.0 | 0.0167 |
| 10 | 30.0 | 0.0333 |
Raw readings and processed values
A results table often has two kinds of column. Raw-data columns hold the values you read directly from an instrument, such as the time on a stopwatch or the volume in a syringe.
Processed columns hold values you calculate from the raw data, such as a mean, a rate, or a percentage change.
Place the raw-data columns first, then the processed columns to their right, so the reader can follow how each calculated value was obtained. Give every processed column a heading that names the quantity and its unit, and show the same number of decimal places down the column.
Constructing a table step by step
- Decide which quantity is the manipulated variable and which is the responding variable.
- Draw the outline with a ruler, giving one column for the manipulated variable, one or more columns for the readings, and a final column for any processed value such as the mean.
- Write a heading in every column that states the quantity and its unit in brackets.
- Enter the manipulated-variable values in the first column in order, usually increasing.
- Record each reading to the precision of the instrument, using the same number of decimal places within a column.
- Calculate any means or rates, and check that every cell is filled.
How tabulation is examined
In the practical paper you may be given a set of readings and asked to arrange them in a suitable table, or to complete a partly drawn table. Marks are awarded for the correct heading with a unit, for the manipulated variable in the first column, for consistent decimal places, and for correctly calculated processed values.
A neat table drawn with a ruler also makes it easier for the examiner to read your data, and it is the first step before you plot a graph or state a conclusion.
Paper 3-style questions
Question 1, tabulation. A student counts the bubbles given off by pondweed in one minute at five light intensities. Describe the table needed to record these results.
Model answer. The table needs a first column for the light intensity (with its unit, such as the distance of the lamp in cm as a measure of intensity) and further columns for the number of bubbles per minute in each trial, followed by a column for the mean number of bubbles per minute. Each heading states the quantity and unit, and the counts are whole numbers recorded consistently.
Question 2, anomalies and means. In three trials at one light intensity the counts are 24, 25 and 38 bubbles per minute. Explain how to deal with this when finding the mean.
Model answer. The reading of 38 is anomalous because it does not fit the pattern of the other two. It should be identified and left out of the calculation, so the mean is (24 + 25) ÷ 2 = 24.5 bubbles per minute.
The reason for excluding it should be noted.
Question 3, processed column. A student measures the time for a colour change at each temperature and wants to show the rate. Explain how to add this to the table.
Model answer. Add a processed column headed 'rate (1/s)' to the right of the time column. Calculate the rate as 1 ÷ time taken for each row, and record every value to the same number of decimal places.
This processed column makes the trend easier to plot and compare.
Common mistakes
Source:SRC-DSKP-EN
Frequently asked questions
Which variable goes in the first column of a results table?
Where should the unit be written in a table?
Why should decimal places be consistent within a column?
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