Survival, Exponential, Accrual, Dropouts: Sample Size Parameters - Quick Tab

Select the Quick tab of the Log-Rank Test: Sample Size Parameters dialog box to access options to establish the basic parameters for analyzing sample size for the 2-group test of equal exponential survival, with an accrual period, with dropouts.

Fixed Parameters

The entries in the boxes under Fixed Parameters establish the fixed, or baseline, parameters for subsequent sample size 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.

Lambda1. In the Lambda1 box, enter the exponential parameter in group 1.

Lambda2

 In the Lambda2 box, enter the exponential parameter in group 2.

Alpha

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

T0. In the T0 box, enter the accrual period.

T.  In the T box, enter the maximum length of the follow up period.

D

 In the D box, enter D, the dropout rate.

Power Goal

In the Power Goal box, enter the minimum acceptable power, for which a minimum sample size is calculated. If the search for an acceptable sample size is successful, the actual power of the statistical test will be greater than or equal to this value.

Type of Hypothesis

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

2-tailed (Lambda2 = Lambda1)

Select the 2-tailed (Lambda2 = Lambda1) option button to use null and alternative hypotheses of the form

H₀: l₂ = l₁ H₁: l₂ ¹ l₁

1-tailed (Lambda2 <= Lambda1)

Select the 1-tailed (Lambda2 >= Lambda1) option button to use null and alternative hypotheses of the form

H₀: l₂ <= l₁ H₁: l₂ > l₁