CT3 IFoA October 2011 Q9(iii) validation

[Satya]

Hello,

I've tried pretty hard but I just cannot reproduce the value of the test statistic that is given in the question in 9.(iii).

I've attached it here. Basically the question says the results give a chi^2 value of 3.332.

However I get a chi^2 value of 1.41. I know that the question doesn't ask you to calculate this (because it's given in the question!).

My method was that the observed values for England, Wales and Scotland are: 62% * 200 people, 53% * 200 people, and so on.
The expected values I used came from summing up the total number of people in favour (=346 people) and proportioning this out equally to each country (=115.3 people per country).
Then I did the usual sum of (Actual-Expected)^2/Expected and this gave me 1.41 (not 3.332).

Really appreciate it if anyone can validate my method?

 

[Satya]

^Please note that I did this exercise just to see if I could reproduce the question. I assume that they only gave the chi^2 value in the question to save time.

 

[John Lee]

I think you forgot the second line in the table of those against the proposal (total 254 people) and expected 84.667 in each.

I get a total of 3.332.

 

[Satya]

Ah yes, that's it... Thanks a lot, don't think I would have spotted it. Just over a week left to iron out mistakes like these!

 

[John Lee]

Glad I could help!