Changes

===Approach for means and proportions===

===Approach for means and proportions===

The general approach for the calculation of confidence intervals in these cases follows the following steps:  

The general approach for the calculation of confidence intervals in these cases follows the following steps:  

* Calculate the sample standard deviation, as an approximation of the population standard deviation:

* Calculate the '''sample standard deviation''', as an approximation of the population standard deviation:

* Estimate the '''standard error of the mean''' or proportion by dividing the sample standard deviation by the square root of the number of animals sampled.

* Estimate the '''standard error of the mean''' or proportion by dividing the sample standard deviation by the square root of the number of animals sampled.

* Calculate the sample mean or proportion (as an approximation of the population mean or proportion).

* Calculate the '''sample mean''' or '''proportion''' (as an approximation of the population mean or proportion).

* Decide upon the confidence level required (usually 95%), and multiply the estimate of the standard error with the appropriate percentile point of the normal distribution (unless you are estimating the confidence interval for the mean of a small sample, in which case the t-distribution should be used instead). In the case of a 95% confidence interval, this is 1.96.

* Decide upon the confidence level required (usually 95%), and '''multiply the estimate of the standard error with the appropriate percentile point of the normal distribution''' (unless you are estimating the confidence interval for the mean of a small sample, in which case the t-distribution should be used instead). In the case of a 95% confidence interval, this is 1.96.

* Subtract the resultant number from the sample mean or proportion to give the lower confidence limit.

* Subtract the resultant number from the sample mean or proportion to give the '''lower confidence limit'''.

* Add the number to the sample mean or proportion to give the upper confidence limit.

* Add the number to the sample mean or proportion to give the '''upper confidence limit'''.