I computed the significance level of gender-related differences in velocity of drug metabolizing capacity among two groups. The p-value I got is exactly 1.0 with Mann–Whitney U test. Is that possible to obtain a p value of 1 in reality?
Yes. When the data is perfectly described by the resticted model, the probability to get data that is less well described is 1. For instance, if the sample means in two groups are identical, the p-values of a t-test is 1.
@Jochen Wilhelm Can we report P=1.00 in manuscript? Does it look wierd?
Stephen Politzer-Ahles
Thanks so much.My data are similar; 0.11% and 0.12%. I did weighing cases and Chi-square. Then P value is 1.00.
Ngozi Louis Uzomah , yes, you can report a p-value of 1. As explained by some answers above, there are cases in which this is the correct value.
I suppose a potential feasible alternative could be "p > 0.999" for those who don't like the look of "p = 1.000".
Hello Melkamu,
You set the significance level (eg 0.05 or 0.10) and compute p-value. These are two different things. P-value range is 0-1 or 0-100%. If it's 1, it's either a rounding up of 0.9999 or that you tested two datasets that have a correlation coefficient of 1.
Regards,
Hello,
I agree with what Faye Anderson reported. You will obtain a P-value=1.000000 if you try to test an evidence like an hypothesis H0 of the form : is the mean1=4,5555555551 equal to the mean2=4.5555555551 where the two means are exactly same reals.
i agree with dr. Chalh. I obtained a p-value of 1 while I was comparing between three models logit , xtlogit and melogit ; the log likelihood for the three were identical. Check the possibility of the two groups to be similar
Hi,
I have analysed the repeatability of behavioural traits using rptR package in a group of fish. I used individual ID as random factor and trial no as the fixed factor. However, for some traits I got a 0 repeatability and a p value of 1. Is this possible? Any suggestions?
The p-value can be exactly 1 in sps, if you use bonferroni correction. To avoid alpha-error cummulation when doing multiple pairwise comparisons sps multiplies the p-values by the number of comparisons.
For example: If you compare 10 pairs every p-value >= 0,100 will be corrected to 1. And because the p-value can't be >1, everey higher value will be limited to 1. These values are exactly 1. You can check this by double-clicking on them.
i have 6 Independent variables. and one of it got 0.217 for p-value while the other 5 variables is
I met it in Fisher Exact test (2x2 table) when one group contains 0 and 14 and the other group contain 4 and 78. However, when the second group contains 9 and 73, the p-value was 0.34.
p value generally not found to be 1. It becomes 1 when values of both groups are same(identical). Here, r= 1. Actually, when p value approaches near to 1 eg 0.99 or .98 it is regarded as 1. Thanks: Prof. Dr Jagadish C Das
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