prctile how to calculate

first of all , my english is not very good if there are many grammatical errors , please include it .

hi,

i don,t know about the method described in the matlab manual for prctile calculation

can you use a set of simple data to explain how the percentile value is calculated?

many thanks

[Rik]

Do you mean you want to know how to use the prctile function with your data?

If not, why do you want to know how it works? Do you want to write your own version?

[peter huang]

Yes, i want to know how prctile calculated the quartiles

ex:

s = [1 2 3 4 5 6 7 8 9 ]

Q1 = prctile(s, 25) % 第一四分位

mean = prctile(s, 50)

Q3 = prctile(s, 75)

Q1 = 2.75 Q3 = 7.25

how did Q1 come

is there any formula?

i need to use my paper

Answer 1

[Star Strider]

See the prctile documentation section on Algorithms.

.

[peter huang]

i readed algorithms but i dont know

is there any clearer calculation of the quartile process?

[peter huang]

ex:

s = [1 2 3 4 5 6 7 8 9 ]

Q1 = prctile(s, 25) % 第一四分位

mean = prctile(s, 50)

Q3 = prctile(s, 75)

Q1 = 2.75 Q3 = 7.25

how did Q1 come

[Rik]

This is not specific to Matlab. Did you read the Wikipedia page?

[Star Strider]

@Rik — Thank you!

@peter huang —

See the discussion under Linear Interpolation.

The documentation explains it better than I can.

.

[Star Strider]

@peter huang —

My pleasure!

If my Answer helped you solve your problem, please Accept it!

.

Answer 2

[peter huang]

@Star Strider thanks i solve my problem successfully