# Quantile - Quantile Plot

A quantile plot plots the number versus its quantile.

The below example shows the plot of response time versus their percentile (from 0 to 1).

## Plot

The two sections below produce the same output.

### R - Application of the Cleveland's formula

Cleveland’s formula on an ordered data set

$f_i = \frac{\displaystyle i-0,5}{\displaystyle n}$

where:

• n is the total number of element
• i is the nth element of an ordered data set
# n calculation
n= length(res_succes$TOTAL_TIME_SEC) # Create a vector from 1 to length of the sample i = 1: n # calculate the value for fi fi = (i - 0.5) / n # Sort the value sorted_values=sort(res_succes$TOTAL_TIME_SEC)
# create a data frame to plot
quantile = data.frame(total_time_sec=sorted_values, quantile_value=fi)

# Render it
ggplot(quantile,aes(x=quantile_plot$quantile_value,y=quantile_plot$total_time_sec)) + geom_point() + xlab("quantile-value")


### Ggplot stat_qq

ggplot(res_succes, aes(sample=res_succes\$TOTAL_TIME_SEC)) + stat_qq(distribution = qunif) + xlab("quantile-value")


where: