What’s the story?

Select the three analytical statements below which, when combined, best summarise this graph’s overall ‘story’.

Identifying the elements of a good AO3 response

Read the two responses to the following 5-mark AO3 question

‘Analyse the relationship between precipitation and runoff for the two river basins shown in the graph.’

Decide which is the best response.

After discussing the strengths and weaknesses of each answer, click to reveal an examiner commentary.

Nodi elfennau ymateb AA3 da

Darllenwch y ddau ymateb i'r cwestiwn AA3 canlynol sy'n werth 5 marc

'Dadansoddwch y gydberthynas rhwng dyodiad a dŵr ffo ar gyfer y ddau fasn afon a ddangosir yn y graff.'

Penderfynwch pa ymateb yw'r un gorau.

Ar ôl trafod cryfderau a gwendidau pob ateb, cliciwch ar y testun i ddatgelu sylwadau'r arholwr.

Response A

In river basin A, overland flow starts off very low when precipitation is also low. For example, 20 millimetres of precipitation result in just 2 millimetres of overland flow. The same is also true of river basin B, for example, when precipitation is about 25 millimetres the overland flow value is only 3 millimetres. Later on, there is an increase in overland flow when precipitation increases. The maximum overland flow for river B is 50 millimetres and for river A it is 60 millimetres. No precipitation value greater than 100 millimetres is recorded for either river.

Examiner Commentary Response A

Although this answer makes plentiful use of data, a clear picture of the relationship between precipitation and overland flow is lacking. There is an absence of important terminology (such as the strength and direction of any correlation). Some of the information provided is superfluous and does not help analyse the relationship. For example, little is gained by telling us that precipitation never exceeds 100mm.

Response B

In both river basins, there is a positive correlation between precipitation and overland flow. However, this is only true when precipitation exceeds 20-30mm. Below this level, there is negligible overland flow in both river basins. For higher values, there is a strong linear relationship between precipitation (pp) and overland flow (O.F.) amounts for river basin A. The highest values reached are 98mm of pp and 60mm of O.F. In river B, the correlation appears a little weaker, for example pp of 70mm and 80mm in both cases produces around 50mm of O.F.

Examiner Commentary Response B

This answer makes good use of data but, more importantly, provides a clear picture of the relationship between the two variables for both river basins. Appropriate terminology is used correctly, such as 'positive correlation' and 'linear relationship’. The answer remains well focused throughout on the strength of any relationship. Overall, this is an excellent structured analysis of the data. Note the way abbreviations are used to make the answer more succinct.

Analysing relationships phrase bank

Here are phrases which can be used to analyse and compare relationships. Now see how many analytical phrases of your own you can add in the right hand column.

Then click on the "Show suggested response" button to reveal other possible key words/phrases. Do any of these phrases match your own? Are any different? Add the extra ones in before printing.

Key phrases used in previous exercises Can you add any more?
There is a positive correlation
There is a strong linear relationship
The correlation appears a little weaker
There is an anomaly shown
The value reaches a threshold

Suggested response

Add these words to the right hand column:

  • Only a weak correlation appears to exist
  • The relationship is nonlinear
  • There is a geometric or exponential rise
  • There are many outliers
  • There is a negative correlation
  • The two variables are inversely related
  • As one variable increases the other declines
  • As one variable falls in value the other grows
  • As x increases, Y also increases but only up to a point