Main Content

Weibull probability plot

`wblplot(`

creates a Weibull probability
plot comparing the distribution of the data in `x`

)`x`

to the Weibull
distribution.

`wblplot`

plots each data point in `x`

using plus sign (`'+'`

) markers and draws two reference lines that
represent the theoretical distribution. A solid reference line connects the first
and third quartiles of the data, and a dashed reference line extends the solid line
to the ends of the data. If the sample data has a Weibull distribution, then the
data points appear along the reference line. A distribution other than Weibull
introduces curvature in the data plot.

returns
graphics handles corresponding to the plotted lines, using any of the input
arguments in the previous syntaxes.`h`

= wblplot(___)

`wblplot`

matches the quantiles of sample data to the quantiles of
a Weibull distribution. The sample data is sorted, scaled logarithmically, and plotted
on the x-axis. The y-axis represents the quantiles of the Weibull distribution,
converted into probability values. Therefore, the y-axis scaling is not linear.

Where the x-axis value is the *i*th sorted value from a sample of
size *N*, the y-axis value is the midpoint between evaluation points of
the empirical cumulative distribution function of the data. The midpoint is equal to $$\frac{\left(i-0.5\right)}{N}$$.

`wblplot`

superimposes a reference line to assess the linearity of
the plot. The line goes through the first and third quartiles of the data.

You can use the `probplot`

function to create a probability
plot. The `probplot`

function enables you to indicate censored data
and specify the distribution for a probability plot.