qqplot

qqplot(x::AbstractVector{AbstractFloat}, y::AbstractVector{AbstractFloat}; kwargs...)

The qqplot function compares the quantiles of two distributions. The qqnorm is a shorthand for comparing a distribution to the normal distribution. If the distributions are similar the points will be on a straight line.

qqplot(x,y, …) displays a quantile-quantile plot of the quantiles of the sample data x versus the quantiles of the sample data y. If the samples come from the same distribution, then the plot appears linear.
qqplot(x, …) displays a quantile-quantile plot of the quantiles of the sample data x versus the theoretical quantile values from a normal distribution. If the distribution of x is normal, then the data plot appears linear. A common used alias to this form is the qqnorm function.

This module is a subset of plot to make it simpler to draw stair plots. So not all (fine) controlling parameters are not listed here. For the finest control, user should consult the module.

Parameters

• qqline : – Determines how to compute a fit line for the Q-Q plot. The options are
  

  • identity: draw the line y = x (the deafult).
  • fit: draw a least squares line fit of the quantile pairs.
  • fitrobust or quantile: draw the line that passes through the first and third quartiles of the distributions.
  • none: do not draw any line.

  Broadly speaking, qqline=:identity is useful to see if x and y follow the same distribution, whereas qqline=:fit and qqline=:fitrobust are useful to see if the distribution of y can be obtained from the distribution of x via an affine transformation.

• For fine the lines settings use the same options as in the module. Nemely lw or lt for controling the line thickness, lc for line color, ls for line styles, etc…

Examples