Hi research student needs urgent help with simple problem

Hi am writing my honours dissertation for sociology and need desperate help calculating a simple problem. Still, I don't even know if it can be done.

Anyway, I asked respondents their ages, they answered as follows:

16 or under (7)
17-25 (20)
25-30 (9)
30 or older (2)
Decline (23)
Total 61

So, is it possible (with the data grouped in this fashion) to calculate the average age?? If so, how?

And if it is possible, how do I interpret this data (if its in a percentile or something)?

It has been a long time since i have done maths, and I have totally forgotten this stuff!
You can't calculate the average ,but you can count the frequency for each group and suggest the most frequently occuring age group (mode).
Are you sure?

Are you sure? I found this website, see here www.geocities.com/socshelby (the password is stormfront), which has very similar data to mine, and this person has a mean and mean percentile calculated.

Look particularly at the question 'What is your age'.

How do I work out 'this' mean and mean percentile?
And, can someone please explain to me what this data means.


TS Contributor
The problem is that your categories are too vague.

Yes, you can estimate a mean from grouped data, but the categories "16 or under" and "30 or older" make this impossible.
What is given in www.geocities.com/socshelby is wrong. Mean suggested here is the mean of codes they used ( 1- 5 ) !! . Even they have calculated the average value of gender (M/F) as 1.333 ! For your problem mode is the most suitable average .
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I see

I see. Thanks for your help. That mean of 'shelbys' really confused me, and I didnt notice the gender thing (although if I had, maybe I would have put two and two together).