Why MS Excel produce diffrent result for the function "Quartile"

[Nadeem Shafique Butt]

I am wondering why Ms Excel produce diffrent result for the Statistical
funtion "Quartile"
e.g

Data
1
2
4
7
8
9
10
12
=QUARTILE(A2:A9,1)
First quartile (25th percentile) of the data above is (3.5), but it should
be 2.5.

Kindly help me in solving this issue

Regards,

Nadeem Shafique

 

[Dave F]

How do you get 2.5 as the first quartile? 3.5 seems correct to me.

Dave

 

[Jerry W. Lewis]

There are several competing approaches to calculating quantiles from sample
data. Excel uses the one that takes the sample max and min to the 0th and
100th percentiles and equally spaces intervening quantiles. This is a
reasonable description of the sample, but is almost certainly biased as an
estimate of the underlying population quantiles. For more details see
http://groups.google.com/group/microsoft.public.excel/msg/011542dcddb69d4e
and the articles referenced in that thread.

Jerry