MedCalc

# Trimmed Mean spreadsheet functions on variables

VTrimMean
VTrimMeanSEM

## Description

VTrimMean and VTrimMeanSEM calculate a trimmed mean and the standard error of a trimmed mean.

VTrimMean(k,variable[,filter]) computes the trimmed mean of a variable.

VTrimMeanSEM(k,variable[,filter]) computes the standard error of the trimmed mean of a variable.

If k is equal to or larger than 1 then k will be taken as the number of cases to drop at each side (if k=1 then 2 cases will be dropped in total).

If k is smaller than 1 then k will be taken as a proportion and n×k cases will be dropped at each side, so a total of 2×n×k cases will be dropped. For example, if k=0.1 then 10% of cases will be dropped at each side; 20% of cases will be dropped in total.

See Calculation of Trimmed Mean, SE and confidence interval for computational details.

## Examples

VTrimMean(0.1,Systolic) calculates the trimmed mean of the data for variable Systolic with 10% of cases dropped at each side: 10% at the lower side and 10% at the higher side.

VTrimMean(3,Systolic) calculates the trimmed mean of the data for variable Systolic with 3 cases dropped at the lower side and 3 cases at the higher side, so a total of 6 cases are dropped.

VTrimMeanLow
VTrimMeanHigh

VTrimMeanLow and VTrimMeanHigh calculate the confidence interval of a trimmed mean of a variable.

VTrimMeanLow(k,ci,variable[,filter]) and VTrimMeanHigh(k,ci,variable[,filter]) compute the lower and higher value of the ci% confidence interval of the trimmed mean of a variable.

The confidence interval ci must be given in the range 0..100. A value of 95 will give the values of a 95% confidence interval.

## Note

This function calculates a statistic on a variable. Be careful when you use this function in cells of the columns that correspond to the variable, because this actually adds a value to the variable which can lead to unexpected and faulty results. You can exclude the cell to avoid this.