Tables, graphs and conclusions

Results are written in a table as you go, then shown on a graph so that patterns are easy to see. From the pattern you write a conclusion: what the results show, and why.

Key facts

  • A results table has the independent variable in the first column and the dependent variable (with each repeat) next. Units go in the headings, not in every box.
  • Mean = the total of the results ÷ how many there are. Leave anomalies out (or repeat them).
  • Range = largest − smallest. A small range means the repeats agree well.
  • Draw a bar chart when the independent variable is categoric (names) and a line graph when it is continuous (measured numbers).
  • On a line graph the independent variable goes along the bottom (x-axis) and the dependent variable up the side (y-axis). Draw a line of best fit through the points.
  • A conclusion describes the pattern (“As the temperature increases, the time to dissolve decreases”) and explains it with science.

Worked examples

Example 1

Sugar dissolving times at 20°C were 62 s, 60 s, 85 s and 61 s. Find the anomaly, then work out the mean of the others.

  1. 62, 60 and 61 are close together. 85 is far from them, so it is the anomaly. Leave it out.
  2. Add the others. 62 + 60 + 61 = 183
  3. Divide by how many there are. 183 ÷ 3 = 61 s

Answer: the anomaly is 85 s; the mean is 61 s

Example 2

The graph shows the temperature of water as it was heated. What was the temperature after 5 minutes, and what is the pattern?

  1. Go up from 5 minutes on the x-axis to the line.
  2. Go across to the y-axis and read the temperature. 50°C
  3. The line is straight: the temperature rises by the same amount each minute. (80 − 20) ÷ 10 = 6°C per minute

Answer: 50°C; the temperature rose steadily, by 6°C every minute

Example 3

A toy car rolled onto four surfaces. The chart shows how far it went (cm). Which surface let it go furthest, and what can you conclude?

  1. The tallest bar is wood: 120 cm.
  2. Carpet and grass are rough and gave the shortest distances; wood and tiles are smooth.
  3. Conclusion: the smoother the surface, the further the car rolls, because there is less friction to slow it down.

Answer: wood; the smoother the surface, the further the car rolls, because there is less friction

Example 4

Three repeats gave 12.4 cm, 12.9 cm and 12.5 cm. Find the mean and the range.

  1. Add the repeats. 12.4 + 12.9 + 12.5 = 37.8
  2. Divide by 3. 37.8 ÷ 3 = 12.6 cm
  3. Range: largest − smallest. 12.9 − 12.4 = 0.5 cm

Answer: mean 12.6 cm; range 0.5 cm