t.and.smd.conversion {MBESS}R Documentation

Conversion functions for noncentral t-distribution

Description

Functions useful for converting a standardized mean difference to a noncentrality parameter, and vise versa.

Usage

lambda2delta(lambda, n.1, n.2)
delta2lambda(delta, n.1, n.2)

Arguments

lambda noncentral value from a t-distribution
delta population value of the standardized mean difference
n.1 sample size in group 1
n.2 sample size in group 2

Details

Although lambda is the population noncentral value, it can be regarded as the observed value of a t-statistics. Likewise, delta can be regarded as the observed standardized mean difference. Thus, the observed standardized mean difference can be converted to the observed t-value. These functions are especially helpful in the context of forming confidence intervals around the population standardized mean difference.

Value

Either the value of delta given lambda or lambda given delta (and the per-group sample sizes).

Author(s)

Ken Kelley (University of Notre Dame; KKelley@ND.Edu)

See Also

smd, ci.smd, ss.aipe.smd

Examples

# lambda2delta(lambda=2, n.1=113, n.2=113)
# delta2lambda(delta=.266076, n.1=113, n.2=113)

[Package MBESS version 2.0.0 Index]