The new school year had barely started when I got a call from a friend who is an elementary school principal. She told me that every morning she announces the names of students who are celebrating a birthday. "One student noticed that we've already had two days on which no student has a birthday," she said. "With 900 students in the school, she thought that at least one birthday should be announced every day. She wants to know more about the math for this situation." What a great question! Th...| The DO Loop
A previous article discusses Cohen's d statistic and how to compute it in SAS. For a two-sample independent design, Cohen's d estimates the standardized mean difference (SMD). Because Cohen's d is a biased statistic, the previous article also computes Hedges' g, which is an unbiased estimate of the SMD. Lastly, the article discusses how to estimate the standard error of the statistic. Today's article extends the analysis by showing how to compute a confidence interval (CI) for Cohen's d (and ...| The DO Loop
SAS provides procedures to fit common probability distributions to sample data. You can use PROC UNIVARIATE in Base SAS or PROC SEVERITY in SAS/ETS software to estimate the distribution parameters for approximately 20 common distributions, including normal, lognormal, beta, gamma, and Weibull. Since there are infinitely many distributions, you may eventually need to fit a distribution that SAS does not natively support. There are three often-used methods for fitting the parameters of a distri...| The DO Loop
In SAS, the INPUT and PUT functions are powerful functions that enable you to convert data from character type to numeric type and vice versa.| The DO Loop
A previous article discusses a formula for a confidence interval for R-square in a linear regression model (Olkin and Finn (1995) "Correlations redux", Psychological Bulletin) The formula is useful for large data sets, but should be used with caution for small samples.| The DO Loop
