how do I calculate t-value when I only know the mean of 10 and 95% confidence interval. I do not know sample size.

Question

Pam Lyerly 2015-6-9

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/223145-how-do-i-calculate-t-value-when-i-only-know-the-mean-of-10-and-95-confidence-interval-i-do-not-kno

编辑： Alfonso Nieto-Castanon 2015-6-9

采纳的回答： Alfonso Nieto-Castanon

how do I calculate t-value when I only know the mean of 10 and 95% confidence interval. I do not know sample size.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Alfonso Nieto-Castanon 2015-6-9

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/223145-how-do-i-calculate-t-value-when-i-only-know-the-mean-of-10-and-95-confidence-interval-i-do-not-kno#answer_182149

编辑：Alfonso Nieto-Castanon 2015-6-9

There are some subtleties depending on how your 95% confidence interval was computed, but typically:

 CI = tinv(.975,N-1)*std(x)/sqrt(N)
 T = mean(x)/std(x)*sqrt(N);

so, if you have the sample mean M (M=mean(x)) and the confience interval CI, you can compute T as:

T = M/CI*tinv(.975,N-1);

If you do not know the sample size N, you may assume N is relatively large and approximate the cumulative T distribution by a cumulative Normal distribution to get:

T = M/CI*1.96;

The subtlety involves how your 95% CI was originally computed. The equation above assumes that this was a two-sided 95% interval (meaning that the population mean of x is expected to lie between M-CI and M+CI with 95% chance). Some times people use one-sided 95% intervals instead (meaning that the population mean of x is expected to be greater than M-CI with 95% chance) and that would mean that in the equations above you would need to change tinv(.975,N-1) to tinv(.95,N-1), and in the last equation change 1.96 to 1.64.