At 17:51 30/01/2022, Richard Goldstein wrote:
>sorry for not being clearer - I am only interested in the inclusion
>of older people - at least at these ages, the distribution is not
>close to being uniform (nor, at least in the few countries I am
>familiar with, it is normal) - further, age is not a response
>variable in any sense; the question is simply whether, based on only
>summary stats, I can infer that people at least 85 (or, at least 65)
>were included in the trial
Maybe I'm misunderstanding, but if the only information you have on
the age distribution in (some or all) of the trials is the mean and
SD, then you can only determine how likely it is that people >65
or >85 were included by making an assumption about the distribution
of ages to which the mean and SD relate.
To take a silly extreme small example, if the ages were (1, 2, 3, 4,
60, 61, 62, 63), the mean would be 32 and the SD about 31.6. If you
assumed a Normal distribution, you might then conclude that about 15%
of the population were over 65 and about 2.5% of the population was
over 95 - even though, in truth, none were over 65!
That is obviously a stupid extreme example, but far more modest
deviations from a Normal Distribution could lead to you drawing
appreciably incorrect conclusions about the proportion of people if
any!) >65 or >85 on the basis of just mean and SD.
Kind Regards,
John
>
https://groups.google.com/d/msgid/medstats/11d3c960-c062-5c73-0cc5-9ead4ce71e5e%40ix.netcom.com.
John
----------------------------------------------------------------
Dr John Whittington, Voice:
+44 (0) 1296 730225
Mediscience Services Fax:
+44 (0) 1296 738893
Twyford Manor, Twyford, E-mail:
Joh...@mediscience.co.uk
Buckingham MK18 4EL, UK
----------------------------------------------------------------