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Confidence intervals for semipartial correlation coefficients are generated using the SCorNB() function from the betaNB package. In this example, we use the data set and the model used in betaNB: Example Using the BetaNB Function.

df <- betaNB::nas1982

Regression

Fit the regression model using the lm() function.

object <- lm(QUALITY ~ NARTIC + PCTGRT + PCTSUPP, data = df)

Nonparametric Bootstrap

nb <- NB(object)

Semipartial Correlation Coefficients

Normal-Theory Approach

out <- SCorNB(nb, alpha = 0.05)

Methods

summary

Summary of the results of SCorNB().

Percentile Confidence Intervals

summary(out, type = "pc")
#> Call:
#> SCorNB(object = nb, alpha = 0.05)
#> 
#> Semipartial correlations
#> type = "pc"
#>            est     se    R   2.5%  97.5%
#> NARTIC  0.4312 0.0683 5000 0.2875 0.5599
#> PCTGRT  0.3430 0.0715 5000 0.1888 0.4690
#> PCTSUPP 0.2385 0.0720 5000 0.0930 0.3750

Bias Corrected Confidence Intervals

summary(out, type = "bc")
#> Call:
#> SCorNB(object = nb, alpha = 0.05)
#> 
#> Semipartial correlations
#> type = "bc"
#>            est     se    R   2.5%  97.5%
#> NARTIC  0.4312 0.0683 5000 0.3025 0.5742
#> PCTGRT  0.3430 0.0715 5000 0.2065 0.4818
#> PCTSUPP 0.2385 0.0720 5000 0.1028 0.3846

Bias Corrected and Accelerated Confidence Intervals

summary(out, type = "bca")
#> Call:
#> SCorNB(object = nb, alpha = 0.05)
#> 
#> Semipartial correlations
#> type = "bca"
#>            est     se    R   2.5%  97.5%
#> NARTIC  0.4312 0.0683 5000 0.3126 0.5840
#> PCTGRT  0.3430 0.0715 5000 0.2156 0.4945
#> PCTSUPP 0.2385 0.0720 5000 0.0985 0.3817

coef

Return the vector of estimates.

coef(out)
#>    NARTIC    PCTGRT   PCTSUPP 
#> 0.4311525 0.3430075 0.2384789

vcov

Return the sampling covariance matrix.

vcov(out)
#>                NARTIC        PCTGRT       PCTSUPP
#> NARTIC   0.0046676875 -0.0004580444 -0.0005958745
#> PCTGRT  -0.0004580444  0.0051159941 -0.0007142684
#> PCTSUPP -0.0005958745 -0.0007142684  0.0051825083

confint

Return confidence intervals.

Percentile Confidence Intervals

confint(out, level = 0.95, type = "pc")
#>              2.5 %    97.5 %
#> NARTIC  0.28754273 0.5598947
#> PCTGRT  0.18884765 0.4690436
#> PCTSUPP 0.09302381 0.3750306

Bias Corrected Confidence Intervals

confint(out, level = 0.95, type = "bc")
#>             2.5 %    97.5 %
#> NARTIC  0.3025181 0.5742005
#> PCTGRT  0.2064524 0.4818210
#> PCTSUPP 0.1028025 0.3846028

Bias Corrected and Accelerated Confidence Intervals

confint(out, level = 0.95, type = "bca")
#>              2.5 %    97.5 %
#> NARTIC  0.31255286 0.5840409
#> PCTGRT  0.21557522 0.4945446
#> PCTSUPP 0.09847316 0.3816628

References