Solution to question 10.1
First we need to calculate the expected values:
| Radiographer 2 | ||||
| Unacceptable | Acceptable | Total | ||
| Radiographer 1 | Unacceptable | 13·3 | 50·7 | 64 |
| Acceptable | 36·7 | 140·3 | 177 | |
| Total | 50 | 191 | 241 | |
So the observed proportion of agreement was:
(31 + 158) ÷ 241 = 0·784
And the expected proportion of agreement was:
(13·3 + 140·3) ÷ 241 = 0·637
So, using the formula:
We get:
κ = (0·784 - 0·637) ÷ (1 - 0·637) = 0·40
Referring to the table in the lecture notes we can see that this value of κ indicates that there is fair agreement between the two radiographers.
