I have 100 patients in sample
men score of 80
and standard deviation of 20
what is the 95% confidence interval?
2007-02-12 21:23:32 · 7 answers · asked by Christian S 2 in Science & Mathematics ➔ Mathematics
do your own homework?
2007-02-12 21:26:12 · answer #1 · answered by Anonymous · 0⤊ 2⤋
To nitpick with cidyah above, he isn't wrong, but few would bother to use the t-distribution with samples that large and with SD calculated from many such samples. The normal distribution would typically be used, and the intervals would be 1.96 SEs wide. Also, the statistics police will get ya' if you use his definition of confidence interval. We are 95% confident that the interval contains the true mean, not that the true mean is within the interval. While it's admittedly a nit, probabilistic statements must be made about statistics (random variables). The limits are statistics; the true mean is not. Said another way, the probability is about our ability to construct such an interval, not about what the true mean is. An even more rigorous definition is that if we repeated this procedure a great many times, we would construct intervals that enclose the true mean 95% of the time. So for any particular procedure, there is a 95% probability that the interval contains the true mean.
2016-03-29 04:36:37 · answer #2 · answered by Anonymous · 0⤊ 0⤋
There is not enough information in the question to answer this unless one makes some assumptions. In particular, one needs to know the distribution of the population you have sampled from. The default assumption is often that one is sampling from a normal distribution (especially for teaching problems). As the sampling distribution of means from a normal population has a t distribution one can use the t distribution to produce a CI.
If so, the 95% CI will be plus or minus t times the standard error of the sample where t is the critical value of the t distribution for alpha equals 0.025 with 99 d.f. (round about 1.96 in a large sample). The standard error is the SD divided by the square root of the sample d.f. so it is 20 divided by root 99 in this case.
2007-02-13 07:54:51 · answer #3 · answered by Thom 2 · 0⤊ 0⤋
the 95% interval should be results between + or - 2* the standard deviation away from the mean.
In your case this is between 40 and 120
2007-02-12 21:37:42 · answer #4 · answered by Mike 5 · 1⤊ 0⤋
Read all about it here: http://www.measuringusability.com/sample_continuous.htm
2007-02-12 22:05:29 · answer #5 · answered by D M L 4 · 0⤊ 0⤋
Huh???????????????????????
2007-02-12 21:27:35 · answer #6 · answered by Jan Frost 3 · 0⤊ 2⤋