# Thread: Acceptable significance level for Chi-Square statistic

1. ## Acceptable significance level for Chi-Square statistic

Hi All,
I need to know if the significance level calculated for a particular Chi-square statistic is less than or equal to 0.05, can we reject the respective null hypothesis?

Cheers,
Sach

2. Hi!
Yes, you can.

Gm

3. Generally, yes. .05 significance is what is usually accepted in the scientific literature, but do not treat .05 as some magic number. It's just the cutoff that they arbitrarily chose; in reality, a p-value of .051 and .049 are basically the same.

4. Originally Posted by squareandrare
Generally, yes. .05 significance is what is usually accepted in the scientific literature, but do not treat .05 as some magic number. It's just the cutoff that they arbitrarily chose; in reality, a p-value of .051 and .049 are basically the same.
You should definitely keep that in mind! So many people I come across put all their hopes into getting a value less than .05 without the acceptance of what was just stated!

5. There is a very nice website
"The Little Handbook of Statistical Practice" and it has really nice history of
Why p = 0.05?

Speaking of p-values for chi-square test. I was asked to create a measure to check how badly people create schedule. The more uniform schedule the better. You don't want to schedule 20 arrivals and 20 departures in one hour - this will overwhelm your workers.

I decided to use chi-square test to test for even distribution of the event during the day. Split 24 hour clock into time buckets, use chi-square test p-value as measure for "uniform" distribution (equal probabilities for each bucket).

It works great, however I would like to have reasonable cut point, I feel that usual p-value of 0.05 and 0.1 still leave lots of bad schedules. Plus we not exactly dealing with random numbers. We will more likely accept null because people do try create reasonable schedule.

I I move my cut point up say to 0.25 or 0.3 I'll get really good results. Can I do this? Well, of course I can, but is it reasonable? Will my explanation above about non-randomness of events be reasonable justification for larger cut point?

Thanks!

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