Thursday, August 5, 2010

Mind Mapping tool

I found that this is quite useful to organize complex problems/projects.
It will let you quickly generate flow diagrams like the one below

Wednesday, August 4, 2010

PROC Power in SAS

Most of us use PASS for sample size calculations, but because PASS is menu-driven, calculations cannot be reproduced without typing in all the parameters from scratch. PROC POWER in SAS is now available and can do many sample size calculations that we commonly use PASS for.  There is also a menu-driven GUI similar to PASS that creates SAS code for later use (just go to Start->Programs->SAS-> SAS Power and Sample Size).

Here is a code snippet for a two-sample t-test and a paired t-test. 

proc power;
   TwoSampleMeans test=diff_satt
      Alpha = 0.05
      Sides = 2
      GroupMeans = (73 -85)    (30 -30)
      GroupStdDevs = (58 70.5) (55.8 68.3) (53.4 66)
      Power = 0.8 0.9
      NPerGroup = .

proc power;
   PairedMeans test = diff
      Alpha = 0.05
      Sides = 2
      PairedMeans = (161.6 106)
      PairedStdDevs = (10.6 73)
      Corr = 0.1 0.3 0.5 0.7
      Power = 0.8 0.9
      NPairs = .


quote on brevity

It came up in yesterday's meeting with Helena and Nikolai. It was Pascal.

"Je N'ai fait celle-ci plus longue que parce que je n'ai pas eu le loisir de la faire plus courte"
"I have only made this letter rather long because I have not had time to make it shorter"
Pascal. Lettres provinciales, 16, Dec.14,1656.

Monday, August 2, 2010

Midwest SAS Users Group Meeting (in Milwaukee)

MWSUG is happening October 10-12 in Milwaukee. Early registration before September 3 is $185, not too bad. For more details and the program see here:

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