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Confidence interval for a standardized linear contrast of means in a between-subjects design

Source: R/statpsych1.R
ci.lc.stdmean.bs.Rd

Computes confidence intervals for a population standardized linear contrast of means in a between-subjects design. The unweighted standardizer is recommended in experimental designs. The weighted standardizer is recommended in nonexperimental designs with simple random sampling. The group 1 standardizer is useful in both experimental and nonexperimental designs. Equality of variances is not assumed. If the group 1 standardizer is used, group 1 would typically be a control group or a comparison group.

For more details, see Section 3.4 of Bonett (2021, Volume 1)

Usage

ci.lc.stdmean.bs(alpha, m, sd, n, v)

Arguments

alpha

alpha level for 1-alpha confidence

m

vector of estimated group means

sd

vector of estimated group standard deviation

n

vector of sample sizes

v

vector of between-subjects contrast coefficients

Value

Returns a 3-row matrix. The columns are:

  • Estimate - estimated standardized linear contrast

  • adj Estimate - bias adjusted standardized linear contrast estimate

  • SE - standard error

  • LL - lower limit of the confidence interval

  • UL - upper limit of the confidence interval

References

Bonett DG (2008). “Confidence intervals for standardized linear contrasts of means.” Psychological Methods, 13(2), 99–109. ISSN 1939-1463, doi:10.1037/1082-989X.13.2.99 .

Bonett DG (2021). Statistical Methods for Psychologists https://dgbonett.sites.ucsc.edu/.

Examples

m <- c(6.94, 7.15, 4.60, 3.68)
sd <- c(2.21, 2.83, 2.29, 1.90)
n <- c(40, 40, 40, 40)
v <- c(.5, .5, -.5, -.5)
ci.lc.stdmean.bs(.05, m, sd, n, v)
#>                          Estimate adj Estimate      SE     LL     UL
#> Unweighted standardizer:   1.2459       1.2399 0.17621 0.9005 1.5912
#> Weighted standardizer:     1.2459       1.2399 0.17313 0.9065 1.5852
#> Group 1 standardizer:      1.3145       1.2890 0.22515 0.8732 1.7558

# Should return:
#                          Estimate adj Estimate      SE     LL     UL
# Unweighted standardizer:   1.2459       1.2399 0.17621 0.9005 1.5912 
# Weighted standardizer:     1.2459       1.2399 0.17313 0.9065 1.5852
# Group 1 standardizer:      1.3145       1.2890 0.22515 0.8732 1.7558