# Bioequivalence and Bioavailability Forum 11:51 CET

libaiyi
Junior

China,
2018-07-12 05:20

Posting: # 19037
Views: 1,365

## Confidence Interval and p value are Con­tradictory [General Sta­tis­tics]

Hi,all

The output of a BE study shows that the confidence interval of all three PK parameters are between 80%-125%. But the p value of AUC0-t's treatment effect is bigger than 0.05, which is in contrast to the conclusion from CI, and the period effect and carryover effect are all proved equal. So, what would be the reason of this contradictory conclusion? All the output are from SAS output.

Thanks in advance.
Helmut
Hero

Vienna, Austria,
2018-07-12 11:09

@ libaiyi
Posting: # 19038
Views: 1,158

## 100% included in 90% CI?

Hi libaiyi,

» The output of a BE study shows that the confidence interval of all three PK parameters are between 80%-125%. But the p value of AUC0-t's treatment effect is bigger than 0.05, which is in contrast to the conclusion from CI, …

I don’t see a contradiction. If the 90% CI contains 100%, the p value will always be >0.05. Only if not, it may be <0.05 (see this lengthy thread).

» … and the period effect and carryover effect are all proved equal.

You can’t prove anything with statistics. Do you mean that the p values are not significant?

Cheers,
Helmut Schütz

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libaiyi
Junior

China,
2018-07-13 08:48

@ Helmut
Posting: # 19042
Views: 1,107

## 100% included in 90% CI?

Hi,Helmut

» I don’t see a contradiction. If the 90% CI contains 100%, the p value will always be >0.05. Only if not, it may be <0.05 (see this lengthy thread).

Sorry I wrote it wrong, it supposed to be that the effect is smaller than 0.05, but I understand now about the meaning of p value.

» You can’t prove anything with statistics. Do you mean that the p values are not significant?

Yes I did mean that the p values are not significant.
Thanks a lot!
zizou
Regular

Plzeň, Czech Republic,
2018-07-17 23:51

@ Helmut
Posting: # 19078
Views: 1,031

## 100% included in 90% CI?

Hi.
» I don’t see a contradiction. If the 90% CI contains 100%, the p value will always be >0.05. Only if not, it may be <0.05 (see this lengthy thread).

Correct & (as mentioned in the mentioned thread) if the 90% CI does not contain 100%, the p value will always be <0.1.

Best regards,
zizou
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