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Dataplot Vol 1 Auxiliary Chapter

COMBINE FREQUENCY TABLE

Name:
    COMBINE FREQUENCY TABLE (LET)
Type:
    Let Subcommand
Purpose:
    Combine low frequency bins in a frequency table.
Description:
    For grouped data, Dataplot typically expects equal width bins. However, there are occasions where you want to combine bins with low frequencies. For example, for the chi-square goodness of fit test it is recommended that the minimum frequency be at least five in order for the chi-square approximation to be valid. This command allows you to automatically combine bins that are below a specified count (5 by default).
Syntax:
    LET <y2> <xlow> <xhigh> = COMBINE FREQUENCY TABLE <y1> <xmid>
                            <SUBSET/EXCEPT/FOR qualification>
    where <y1> is a variable containing the original frequencies;
                <xmid> is a variable containing the bin mid-points;
                <y2> is a variable where the combined frequencies are stored;
                <xlow> is a variable where the lower limits for the combined bins are stored;
                <xhigh> is a variable where the upper limits for the combined bins are stored;
    and where the <SUBSET/EXCEPT/FOR qualification> is optional.
Examples:
    LET Y2 XLOW XHIGH = COMBINE FREQUENCY TABLE Y XMID
Note:
    You can specify the minimum frequency for a bin by entering the command

      LET MINSIZE = <value>

    before the COMBINE FREQUENCY TABLE command.

Note:
    The following commands currently accept grouped data with either equal size bins or unequal size bins:

      PROBABILITY PLOT
      PPCC PLOT
      KS PLOT
      CHI-SQUARE GOODNESS OF FIT
Default:
    The minimum frequency for a bin defaults to 5.
Synonyms:
    None
Related Commands: Applications:
    Distributional Modeling
Implementation Date:
    2004/10
Program:
     
    LET Y = LOGNORMAL RANDOM NUMBERS FOR I = 1 1 100
    LET Y1 XMID = BINNED Y
    PRINT Y1 XMID
    LET Y2 XLOW XHIGH = COMBINE FREQUENCY TABLE Y1 XMID
    PRINT Y2 XLOW XHIGH
    TITLE AUTOMATIC
    Y1LABEL CORRELATION
    X1LABEL SIGMA
    LOGNORMAL PPCC PLOT Y2 XLOW XHIGH
        
     VARIABLES--Y1             XMID    
    
       0.6000000E+01  0.2812552E-01
       0.2000000E+02  0.4171193E+00
       0.2400000E+02  0.8061130E+00
       0.1400000E+02  0.1195107E+01
       0.1300000E+02  0.1584100E+01
       0.7000000E+01  0.1973094E+01
       0.5000000E+01  0.2362088E+01
       0.1000000E+01  0.2751082E+01
       0.1000000E+01  0.3140075E+01
       0.1000000E+01  0.3529069E+01
       0.1000000E+01  0.3918063E+01
       0.3000000E+01  0.4307056E+01
       0.0000000E+00  0.4696051E+01
       0.2000000E+01  0.5085044E+01
       0.1000000E+01  0.5474038E+01
       0.0000000E+00  0.5863031E+01
       0.0000000E+00  0.6252026E+01
       0.0000000E+00  0.6641019E+01
       0.0000000E+00  0.7030013E+01
       0.1000000E+01  0.7419006E+01
    
    
     VARIABLES--Y2             XLOW           XHIGH   
    
       0.6000000E+01 -0.1663711E+00  0.2226222E+00
       0.2000000E+02  0.2226226E+00  0.6116159E+00
       0.2400000E+02  0.6116164E+00  0.1000610E+01
       0.1400000E+02  0.1000610E+01  0.1389603E+01
       0.1300000E+02  0.1389604E+01  0.1778597E+01
       0.7000000E+01  0.1778598E+01  0.2167591E+01
       0.5000000E+01  0.2167591E+01  0.2556585E+01
       0.1100000E+02  0.2556585E+01  0.7613503E+01
        
    plot generated by sample program

Date created: 11/7/2005
Last updated: 11/7/2005
Please email comments on this WWW page to alan.heckert@nist.gov.