Final answer:
The average causal effect of college education on wages for individuals A and B is £9 per hour.
Step-by-step explanation:
The question is about calculating the average causal (treatment) effect of college education on hourly wages for two individuals, A and B. To find the average effect, we calculate the hourly wage increase for each individual due to college education and then find the average of these increases. For individual A, the wage increase is £24 - £12 = £12. For individual B, the increase is £14 - £8 = £6. The average causal effect is therefore (£12 + £6) / 2 = £9 per hour.