9/20/2010

Ties Corrections

The W* LSA test in the case of ties is conservative if we do not use the correction. i.e., If we reject the null hypothesis without the correction, then we would also reject the null hypothesis with it.

General recommendation:

• Compute W* without the ties correction
• Find the p-value for this uncorrected W*. If the p-value is less than or equal to alpha, reject the null hypothesis and do not mess with the ties correction.
• If the p-value is greater than alpha, but close to alpha, then use the ties correction and recompute alpha.
• If the p-value is greater than alpha, but not close to alpha, ignore the ties correction.

Point and Interval Estimation for Shift Parameter

Please read Sections 4.2, 4.3, and 4.4 for class on Wednesday.