How do i calculate the upper quartile, lower quartile and inter quartile range with have 9 pieces of data?

any help would be much appreciated





my values have decimals as well. so im not sure how to do it.|||This is an unfortunate area in statistics. Basically there is no generally agreed upon definition for the upper %26amp; lower quartiles. It goes something like this:





The median is well defined for any finite set of numbers. Just list them in order and it's the one in the middle (if there are an odd # of numbers to begin with) or the mean (average) of the 2 in the middle (if there are an even # of numbers to begin with). So far, so good.





The lower quartile is generally limited by the median of the "lower half" of the original set of numbers. Unfortunately, if there is an odd # of numbers to begin with, some authors include the median itself in the "lower half" and some do not. Also a problem is whether to include the 'median of the lower half' in the bottom quartile, or in the second.





In spreadsheets, and in various Stat. Packages I've seen it various ways.





Now, if the # of original numbers is very large this will not usually make much difference, but with only 9 there are going to be problems.





Of course, the upper quartile has the same difficulty.


|||quartiles means that u divide the number of pieces by 4, and multiply by 1 for lower quartile, and 3 for the upper quartile:


9*1/4 = 2.25, so the lower quartile is 2


9*3/4 = 6.75, so the upper quartile is 7


i suppose that IQR = Q3 - Q1 = 7 -2 = 5