Adding reference lines for sigma to a distribution histogram

mbwun

I would like to customize my distribution histogram by adding reference lines for +/- 3 sd but I can't figure out how to get the 'Std Dev' without entering it manually.

What I am looking for is a customization that can be pasted into many separate distribution plots.

Any suggustions would be most helpful. - Tim

ptkguy

One way to get column stats is with summarize():

dt = Open("$ENGLISH_SAMPLE_DATA/Big Class.jmp");

//Get column stats

summarize(

  sigma=StdDev(:height),

  avg = mean(:height)

);

siglow = avg - 3 * sigma;

sighigh = avg + 3 * sigma;

//make distribution

Distribution(

  Continuous Distribution( Column( :height ), Count Axis( 1 ) ),

  SendToReport(

  Dispatch(

  {"height"},

  "1",

  ScaleBox,

  {

  Min( 45 ), Max( 78), Inc( 5 ),Minor Ticks( 1 ),

  Add Ref Line( eval(siglow), Dotted, "Black","-3sd" ),

  Add Ref Line( eval(sighigh), Dotted, "Black","+3sd" )

  }

  )

  )

);