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).


The two sections below produce the same output.

R - Application of the Cleveland's formula

Cleveland’s formula on an ordered data set

<math> f_i = \frac{\displaystyle i-0,5}{\displaystyle n} </math>


  • 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
# 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")


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