Reliable change index — rci • scan

The rci() function computes indices of reliable change (Wise, 2004) and corresponding descriptive statistics.

Usage

rci(data, dvar, pvar, rel, ci = 0.95, graph = FALSE, phases = c(1, 2))

Arguments

data: A single-case data frame. See scdf() to learn about this format.
dvar: Character string with the name of the dependent variable. Defaults to the attributes in the scdf file.
pvar: Character string with the name of the phase variable. Defaults to the attributes in the scdf file.
rel: Reliability of the measure, used to compute the standard error.
ci: Width of confidence interval as a decimal. Default is ci = 0.95 applying a 95 percent confidence interval.
graph: If set TRUE, a box plot of phase A and B scores is displayed. graph = FALSE by default.
phases: A vector of two characters or numbers indicating the two phases that should be compared. E.g., phases = c("A","C") or phases = c(2,4) for comparing the second to the fourth phase. Phases could be combined by providing a list with two elements. E.g., phases = list(A = c(1,3), B = c(2,4)) will compare phases 1 and 3 (as A) against 2 and 4 (as B). Default is phases = c(1,2).

References

Christensen, L., & Mendoza, J. L. (1986). A method of assessing change in a single subject: An alteration of the RC index. Behavior Therapy, 17, 305-308.

Jacobson, N. S., & Truax, P. (1991). Clinical Significance: A statistical approach to defining meaningful change in psychotherapy research. Journal of Consulting and Clinical Psychology, 59, 12-19.

Wise, E. A. (2004). Methods for analyzing psychotherapy outcomes: A review of clinical significance, reliable change, and recommendations for future directions. Journal of Personality Assessment, 82, 50 - 59.

Author

Juergen Wilbert

Examples


## Report the RCIs of the first case from the byHeart data and include a graph
rci(byHeart2011[1], graph = TRUE, rel = 0.8)

#> Reliable Change Index
#> 
#> Mean Difference =  12.4 
#> Standardized Difference =  1.691 
#> Standard error of differences =  0.346 
#> Reliability of measurements =  0.8 
#> 
#> Descriptives:
#>         n mean    SD    SE
#> A-Phase 5  0.4 0.548 0.245
#> B-Phase 5 12.8 5.634 2.520
#> 
#> 95 % Confidence Intervals:
#>          Lower  Upper
#> A-Phase -0.080  0.880
#> B-Phase  7.862 17.738
#> 
#> Reliable Change Indices:
#>                            RCI
#> Jacobson et al.         50.623
#> Christensen and Mendoza 35.796
#>