Simple statistical analysis

[StuartR]

It is a long time since I had to do any statistical analysis.

I have a set of "things", which are named "Thing 1", "Thing 2" etc. up to "Thing 20"
I have a number of events associated with each of these things.
I need to demonstrate whether the distribution of events shows a significant difference between the things, or whether it is just as likely to be random.
Can someone please tell me what to do to generate a significance rating

The numbers I have are

Thing	Event Count
1	5
2	8
3	1
4	1
5	0
6	0
7	6
8	0
9	0
10	3
11	0
12	1
13	0
14	0
15	1
16	0
17	0
18	1
19	0
20	2

[Jan Karel Pieterse]

Are there no replications in there, so we can assess the variability?

[StuartR]

I guess what I would like to be able to state is whether the high values for things 7 and 2 are significant, or are they likely to be chance.

In other words is the variable number of events per thing significant, or would you expect this number of events to have such an uneven distribution.

[Jan Karel Pieterse]

I don't have a boilerplate answer for you, this is beyond my expertise.
Maybe this page can give you some clues:
http://www.statsoft.com/textbook/basic- ... %20samples

[Jan Karel Pieterse]

ANd perhaps this one (same site):
http://www.statsoft.com/textbook/statis ... /?button=3

[HansV]

To test whether data are uniformly distributed, you can use the chi-square test. As the attached workbook shows, the chi-square value for this sample is ~69.6, with 19 degrees of freedom (20-1).
The p-value is =CHIDIST(69.6, 19) ~ 10^-7, i.e. it is extremely improbable that these data are uniformly distributed.

ChiSquareTest.xls

[StuartR]

Hans,

That is exactly what I was looking for, thank you.

I remember doing chi-square calculations when I was studying zoology at school, many decades ago, but I couldn't remember any detail about it, even the name.

Jan Karel
Thanks for the pointers. There's lots of good stuff to read there.

[Jan Karel Pieterse]

Yes, an excellent resource if you ask me. They used to have a downloadable version of the textbook too, but I can't find it anymore. I do have it on my system though.