Hi,
Could someone explain to me or point out some documentation on how to compute a given percentile from a histogram ?
Hi, Could someone explain to me or point out some documentation on how to compute a given percentile from a histogram ? 

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A histogram gives you the number $n_i$ of observations between some $x_i$ and $x_{i+1}$. I'm assuming a total of $n$ observation. So, to get an approximation for the upper $p$percentile, you want to find the maximal $j$ such that $\sum_{i=j}^\infty n_i\geq p*n$. Then, the empirical upper $p$percentile is between $x_j$ and $x_{j+1}$. 

