4 After a holiday organised for a group, the company organising the holiday obtained scores out of 10 for six different aspects of the holiday. The company obtained responses from 100 couples and 100 single travellers. The total scores for each of the aspects are given in the following table.
| Aspect | Couples | Single travellers |
| Organisation | 884 | 867 |
| Travel | 710 | 633 |
| Food | 692 | 675 |
| Leader | 898 | 898 |
| Included visits | 561 | 736 |
| Optional visits | 683 | 712 |
Fred wishes to test whether there is significant positive correlation between the scores given by the two categories.
- Explain why it is probably not appropriate to use Pearson's product-moment correlation coefficient.
- Carry out an appropriate test at the \(1 \%\) level.
- Explain what is meant by the statement that the test carried out in part (b) is a non-parametric test.