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StatProbPlots.StatQQPlot Function
StatProbPlots | Functions

Constructs an Q-Q plot of the quantiles of the data set Data againsts the quantiles of a standard Normal distribution.

Pascal
procedure StatQQPlot(const Data: TVec; const XDrawVec: TVec; const YDrawVec: TVec; out MinX: double; out MaxX: double; out MinY: double; out MaxY: double; const DataSorted: boolean = true); overload;
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Description

How to construct Q-Q normal distribution probability plot?

  1. If needed, Data values are sorted (DataSorted parameter set to false).
  2. Abscissa drawing values are formed by estimated data quantiles - ordered Data values. After calculation they are copied to XDrawVec. crefTMtxVecBase.Length and crefTMtxVec.Complex properties of XDrawVec are adjusted automatically.
  3. Ordinate drawing values are formed by using theoretical probabilitie p i.e the so Z values. After calculation they are copied to XDrawVec. crefTMtxVecBase.Length and crefTMtxVec.Complex properties of XDrawVec are adjusted automatically.
  4. XDrawVec and YDrawVec 25th and 75th percentile points are used to construct a reference line. Drawing points departures from this straight line indicate departures from normality.
Notes

Use this overload if you want to check if specific data comes from standard Normal distribution (mean = 0, sigma^2 = 1.0)

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