CODE DEX 2-LEVEL

CODE DEX 2-LEVEL (LET)

Let Subcommand

Generate a coded variable for a factor variable used in analyzing a 2-level full or fractional factorial design.

To analyze a 2-level full or fractional factorial design, the factor variable are typically coded with lower level set to -1, the upper level set to +1, and center points set to 0. This will be referred to as classical units.

If your factor variables are in original units of the data rather than classical units, you can use the CODE DEX 2-LEVEL command to convert them to classical units.

In some cases, you may only want the minimum and maximum values (i.e., the "-1" and "+1" points). For example, for the dex interaction effects plot in the ten step analysis we need exactly two levels.

This command is similar to the CODE DEX command. The distinction is that CODE DEX preserves the center points and expects a maximum of the 3 distinct values. The CODE DEX 2-LEVEL command will accept any number of levels, but only saves the minimum and maximum levels.

LET <y> = CODE DEX 2-LEVEL <x>
                        <SUBSET/EXCEPT/FOR qualification>
where <x> is the factor variable;
            <y> is a variable where the coded values are saved;
and where the <SUBSET/EXCEPT/FOR qualification> is optional.

LET X2OUT = CODE DEX 2-LEVEL X2

You can use the same name for the input variable and the output variable. For example
LET X2 = CODE DEX 2-LEVEL X2

If you want to have variables in the original units for some purposes, you can save the data in original units before using the CODE DEX 2-LEVEL command. For example

LOOP FOR J = 1 1 K

LET Z^J = X^J
LET X^J = CODE DEX 2-LEVEL Z^J

END OF LOOP

None

DEX CODE 2-LEVEL
CODE DEX 2LEVEL
DEX CODE 2LEVEL

CODE DEX	=	Convert to classic units but preserve center points.
DEX CHECK CLASSIC	=	Determine if your factor variables are in classic units.
CODE	=	Generate a coded variable based on distinct values.

Analysis of 2-level full and fractional factorial designs

2018/10

 
read x1
24
36
24
36
24
36
24
36
30
30
end of data
.
set write decimals 0
let y1 = code dex x1
let y2 = code dex 2-level x1
print x1 y1
print y2
    

The following output is returned

 
------------------------------
             X1             Y1
------------------------------
             24             -1
             36              1
             24             -1
             36              1
             24             -1
             36              1
             24             -1
             36              1
             30              0
             30              0
 
 
---------------
             Y2
---------------
             -1
              1
             -1
              1
             -1
              1
             -1
              1