Log-Rank Test: Power Calculation Parameters - Quick Tab

Select the Quick tab of the Log-Rank Test: Power Calculation Parameters dialog box to access options to enter baseline parameters for power calculations for the log-rank test for equality of two survival curves.

Fixed Parameters. The entries in the boxes under Fixed Parameters establish the fixed, or baseline, parameters for subsequent power calculations and graphs. Parameters that are not varied explicitly as the independent (X-axis) variables in a graphical analysis will be set equal to these values.

Pi1. In the Pi1 box, enter the survival rate in group 1.

Pi2. In the Pi2 box, enter the survival rate in group 2.

N. In the N box, enter N, the sample size.

Alpha. In the Alpha box, enter the type I error rate for the overall significance test.

Type of Hypothesis. Use the option buttons under Type of Hypothesis to determine the type of null hypothesis tested.

2-tailed (Pi1 = Pi2). Select the 2-tailed (Pi1 = Pi2) option button to use null and alternative hypotheses of the form

H0: p1 = p2 H1: p1 ¹ p2

1-tailed (Pi1 >= Pi2). Select the 1-tailed (Pi1 >= Pi2) option button to use null and alternative hypotheses of the form

H0: p1 ³ p2 H1: p1 < p2