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AQA GCSE · Question 08.3 · Data Visualization and Representation
Here is some information about the results sampled for later in the day.
- After 12.30pm but before 1.30pm all five customers sampled waited between 4 and 5 minutes.
- From 1.30pm, the six results showed a strong negative correlation.
Describe the correlation shown by each of these two new sets of data.
Here is some information about the results sampled for later in the day.
- After 12.30pm but before 1.30pm all five customers sampled waited between 4 and 5 minutes.
- From 1.30pm, the six results showed a strong negative correlation.
Describe the correlation shown by each of these two new sets of data.
How to approach this question
1. **Analyse the first piece of information**: "After 12.30pm but before 1.30pm all five customers sampled waited between 4 and 5 minutes."
* 12.30pm is 3.5 hours after 9am = 210 minutes. 1.30pm is 4.5 hours after 9am = 270 minutes. So, x-values are between 210 and 270.
* The y-values (waiting time) are all between 4 and 5.
* If you plotted these points, they would form a horizontal cluster. A horizontal line has no slope, which means there is **no correlation**.
2. **Analyse the second piece of information**: "From 1.30pm, the six results showed a strong negative correlation."
* The question explicitly states the correlation type.
* Describe what this means: as one variable (time) increases, the other variable (waiting time) decreases.
3. Write down the description for each part.
Full Answer
This question tests the understanding of what different patterns on a scatter diagram mean in terms of correlation.
* **First period (12.30pm - 1.30pm)**: The information states that all customers waited between 4 and 5 minutes. This means the y-values of the data points would be clustered in a narrow horizontal band at the top of the graph. As the x-value (time) increases, the y-value (waiting time) does not systematically increase or decrease; it stays roughly constant. This pattern represents **no correlation** (or very weak correlation).
* **Second period (From 1.30pm)**: The question explicitly states that these results showed a **strong negative correlation**. This means that as the time of day got later, the waiting time for customers got shorter. On a graph, the points would trend downwards from left to right.
Common mistakes
✗ For the first part, guessing positive or negative correlation instead of realising the horizontal pattern means no correlation.
✗ Simply writing "negative correlation" for the second part without the word "strong", which was given in the question.
Practice the full AQA GCSE Statistics Higher Tier Paper 1
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