h = qqplot(X,Y,pvec)
qqplot(X) displays a quantile-quantile
plot of the sample quantiles of
X versus theoretical
quantiles from a normal distribution. If the distribution of
normal, the plot will be close to linear.
qqplot(X,Y) displays a quantile-quantile
plot of two samples. If the samples do come from the same distribution,
the plot will be linear.
qqplot(X,PD) makes an empirical
quantile-quantile plot of the quantiles of the data in the vector
the quantiles of the distribution specified by
ProbDist object of the
ProbDistUnivParam class or
a separate line for each pair of columns. The plotted quantiles are
the quantiles of the smaller data set.
The plot has the sample data displayed with the plot symbol
Superimposed on the plot is a line joining the first and third quartiles
of each distribution (this is a robust linear fit of the order statistics
of the two samples). This line is extrapolated out to the ends of the sample to help evaluate
the linearity of the data.
qqplot(X,Y,pvec) to specify the quantiles
in the vector
h = qqplot(X,Y,pvec) returns
handles to the lines in
This example shows how to create a quantile-quantile plot using two sets of sample data.
Generate random numbers from two Poisson distributions. The vector
x contains 50 random numbers from a Poisson distribution with
lambda = 10. The vector
y contains 100 random numbers from a Poisson distribution with
lambda = 5.
rng default; % For reproducibility x = poissrnd(10,50,1); y = poissrnd(5,100,1);
Create a quantile-quantile plot using the two sets of sample data.
The solid line in the plot joins the first and third quartiles. The dashed line extrapolates the solid line.