Statistics
Percentile rank with the population convention
Divides by the group size itself, treating the group as the whole population. For the same data this gives 238 / 250 = 0.952.
The Formula
PR = count below / n
Divides by the group size itself, treating the group as the whole population. For the same data this gives 238 / 250 = 0.952.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| PR | Percentile rank as a proportion | dimensionless | 0.952 for the worked case, always slightly below the sample-convention value. |
| count below | Number of values strictly below the value of interest | count | 238 here, the same count used by the sample convention. |
| n | Size of the group | count | 250 here; dividing by it gives the simple proportion below. |
What Each Symbol Means
PRdimensionless
Percentile rank as a proportion
0.952 for the worked case, always slightly below the sample-convention value.
count belowcount
Number of values strictly below the value of interest
238 here, the same count used by the sample convention.
ncount
Size of the group
250 here; dividing by it gives the simple proportion below.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate a percentile rank page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate A Percentile Rank, filed under Education. Every number the guide produces comes from substituting into this one line.