NAPBF_twoz: Bayes factor in favor of the NAP in two-sample z tests

Description Usage Arguments Details Value Author(s) References Examples

View source: R/NAPfunctions.R

Description

In case of two independent populations N(μ_1,σ_0^2) and N(μ_2,σ_0^2) with known common variance σ_0^2, consider the two-sample z-test for testing the point null hypothesis of difference in their means H_0 : μ_2 - μ_1 = 0 against H_1 : μ_2 - μ_1 \neq 0. Based on an observed data, this function calculates the Bayes factor in favor of H_1 when a normal moment prior is assumed on the difference between standardized effect sizes (μ_2 - μ_1)/σ_0 under the alternative.

Usage

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NAPBF_twoz(obs1, obs2, n1Obs, n2Obs, 
           mean.obs1, mean.obs2, test.statistic, 
           tau.NAP = 0.3/sqrt(2), sigma0 = 1)

Arguments

obs1

Numeric vector. Observed vector of data from Group-1.

obs2

Numeric vector. Observed vector of data from Group-2.

n1Obs

Numeric or numeric vector. Sample size(s) from Group-1. Same as length(obs1) when numeric.

n2Obs

Numeric or numeric vector. Sample size(s) from Group-2. Same as length(obs2) when numeric.

mean.obs1

Numeric or numeric vector. Sample mean(s) from Group-1. Same as mean(obs1) when numeric.

mean.obs2

Numeric or numeric vector. Sample mean(s) from Group-2. Same as mean(obs2) when numeric.

test.statistic

Numeric or numeric vector. Test-statistic value(s).

tau.NAP

Positive numeric. Parameter in the moment prior. Default: 0.3/√{2}. This places the prior modes of (μ_2 - μ_1)/σ_0 at 0.3 and -0.3.

sigma0

Positive numeric. Known common standard deviation of the populations. Default: 1.

Details

Value

Positive numeric or numeric vector. The Bayes factor value(s).

Author(s)

Sandipan Pramanik and Valen E. Johnson

References

Pramanik, S. and Johnson, V. (2022). Efficient Alternatives for Bayesian Hypothesis Tests in Psychology. Psychological Methods. Just accepted.

Johnson, V. and Rossell, R. (2010). On the use of non-local prior densities in Bayesian hypothesis tests. Journal of the Royal Statistical Society: Series B, 72:143-170. [Article]

Examples

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NAPBF_twoz(obs1 = rnorm(100), obs2 = rnorm(100))

NAP documentation built on Jan. 6, 2022, 5:07 p.m.