Friday, April 28, 2006

A joke about statistician

Even thoug this is a joke, I find sometimes it is very true.

A manager wanted to hire someone to work in her department and she had applications from a lawyer, an archeologist, and a statistician. She invited the lawyer for an interview and asked just a single question, "What is one plus one?" The lawyer explained "In matters of commercial law, the Supreme Court precedent in 1867 established that, in matters of commercial law, one plus one is considered to be prima facie evidence of equaling two." The manager was very impressed. Then she invited the archeologist for an interview and asked the same question. The archeologist replied, "Although many ancient cultures had solid concepts of numbers, the concept of addition was first established in the Egyptian culture, circa 2000 B.C. and it was at the tomb of Amenhotep that the first written evidence was found to establish that one plus one was equal to two." Again the manager was very impressed. She then invited the statistician in and asked "What is one plus one?" The statistician looked around very carefully, then went up and closed the door, lowered the window shades, and asked very quietly "What do you want it to be?"

Sample size considering the drop out rate

Thanks for my colleagure who point out my mistake in calculating the sample size adjusting for the drop out rate. According to the sample size calculation, we estimated that 100 subjects would be needed to detect the statistical differences. Considering 20% drop out rate, what is the # of subjects to be randomized?
It is not 100 + 100*20% = 120
It should be 100 / (1-0.2) = 125
It means that with 125 randomized subjects, if 25 subjects (20% of 125) drop out, we still have 100 subjects left. This is correct way to adjust for the drop out rate.


I am surprised to know that there is a SAS procedure for CDISC. Is this procedure really working?