when the data points are organized they are placed in ascending order based on those prices that fell the most to the prices that rose the most specific percentages are removed from the tails to help lower the effect of volatility on the overall cpi changes 
trimmed means are used in the olympics to remove extreme scoring from possibly biased judges who may impact an athlete s average score 3providing a trimmed mean inflation rate along with other measures provides a basis for comparison allowing for a more thorough analysis of the inflation rates being experienced this comparison may include the traditional cpi the core cpi a trimmed mean cpi and a median cpi example of a trimmed meanlet s say as an example a figure skating competition produces the following scores 6 0 8 1 8 3 9 1 and 9 9 the mean for the scores would equal to trim the mean by a total of 40 we remove the lowest 20 and the highest 20 of values eliminating the scores of 6 0 and 9 9 next we calculate the mean based on the calculation in other words a mean trimmed at 40 would equal 8 5 vs 8 28 which reduced the outlier bias and had the effect of increasing the reported average by 0 22 points 