Dear all,

I need your advice on the following situation. I have a developmental test and I need to calculate the 2nd and 25th percentile points for ten different age groups. The dataset contains discrete values, the sample size ranges from 35-52 and in each age category there are several replicates of the same values (ties). I use R's quantile function, but it has 9 different ways of calculating the percentile points. While for the 25th percentile point all methods converge to the same value there are several discrepancies at the 2nd percentile point. So my question is which method is appropriate for this particular data.

Thank you,