It is important to process and present data in a way which makes it easy to analyse. It is also important to evaluate the quality of data before drawing a conclusion.

The best way to display collected data is in a table. This helps to organise your data collection.

The following are good guidelines when presenting results in tables:

- if drawing a table by hand use a ruler and a pencil
- column headings should show quantity and unit
- independent variable in the first column and dependent variables in columns to the right
- all results for a particular quantity should be recorded to the same number of decimal places
- no units in the body of the table

A student has been investigating how the time for ten swings of a pendulum varies with length. They record the following results:

Length (cm) | Attempt 1 (s) | Attempt 2 (s) | Attempt 3 (s) | Average time for ten swings (s) |
---|---|---|---|---|

20 | 8.7 | 8.8 | 9.2 | 8.9 |

40 | 12.6 | 12.4 | 12.8 | 12.6 |

60 | 15.3 | 15.3 | 15.5 | 15.4 |

80 | 17.9 | 18.0 | 17.6 | 17.8 |

100 | 20.0 | 19.8 | 20.0 | 19.9 |

When doing calculations with measured answers, the answer should have the same number of significant figures as the measured value.

When rounding a number that has more significant figures than are justified, round up if the last figure is between 5 and 9 inclusive, if it is between 0 and 4 inclusive round down.

For example, the number 3.5099 rounded to:

- 4 significant figures is 3.510
- 3 significant figures is 3.51
- 2 significant figures is 3.5
- 1 significant figure is 4

Charts are a way to display data after it has been collected.

Discrete data can only have certain values and are shown using a bar chart. This can help to show any patterns.

A pie chart shows a category compared with the whole. For example, the percentage of each energy source used in the UK can be shown using a pie chart.

Continuous data can take any value in a given range. It includes time, mass and length.

Continuous data should be presented on a line graph. Line graphs are particularly useful in helping to spot any trends or patterns in the data. For example, the relationship between current and voltage for a resistor.

The following is best practice when drawing graphs:

- use a ruler and pencil to draw the axis
- label the axis with the quantity and the unit it is measured in
- the independent variable should be plotted on the X-axis and the dependent variable should be plotted on the Y-axis
- use an appropriate scale for your axis - this should lead to a graph that uses more than 50% of the paper
- when drawing a line or curve of best fit there must be a reasonable balance of plots either side of the line
- a ruler should be used to draw a straight line of best fit
- when the data produces a curve, the curve should be drawn smoothly free-hand