REGIONS_OF_SIGNIFICANCE {SIMPLE.REGRESSION}

Plots of Johnson-Neyman regions of significance for interactions

Description

Plots of Johnson-Neyman regions of significance for interactions in moderated multiple regression, for both MODERATED_REGRESSION models (which are produced by this package) and for lme models (from the nlme package).

Usage

REGIONS_OF_SIGNIFICANCE(model,
                        IV_range=NULL, MOD_range=NULL,
                        plot_title=NULL, Xaxis_label=NULL,
                        Yaxis_label=NULL, legend_label=NULL,
                        names_IV_MOD=NULL)

Arguments

model

The name of a MODERATED_REGRESSION model, or of an lme model from the nlme package.

IV_range

(optional) The range of the IV to be used in the plot.
Example: IV_range = c(1, 10)

MOD_range

(optional) The range of the MOD values to be used in the plot.
Example: MOD_range = c(2, 4, 6)

plot_title

(optional) The plot title.
Example: plot_title = 'Regions of Significance Plot'

Xaxis_label

(optional) A label for the X axis to be used in the plot.
Example: Xaxis_label = 'IV name'

Yaxis_label

(optional) A label for the Y axis to be used in the plot.
Example: Yaxis_label = 'DV name'

legend_label

(optional) The legend label.
Example: legend_label = 'Simple Slopes'

names_IV_MOD

(optional) and for lme/nlme models only. Use this argument to ensure that the IV and MOD variables are correctly identified for the plot. There are three scenarios in particular that may require specification of this argument:

• when there are covariates in addition to IV & MOD as predictors,

• if the order of the variables in model is not IV then MOD, or,

• if the IV is a two-level factor (because lme alters the variable names in this case).

Example: names_IV_MOD = c('IV name', 'MOD name')

Value

A list with the following possible components:

JN.data

The Johnson-Neyman results for a moderated regression.

ros

The Johnson-Neyman regions of significance for a moderated regression.

Author(s)

Brian P. O'Connor

References

Bauer, D. J., & Curran, P. J. (2005). Probing interactions in fixed and multilevel regression: Inferential and graphical techniques. Multivariate Behavioral Research, 40(3), 373-400.

Huitema, B. (2011). The analysis of covariance and alternatives: Statistical methods for experiments, quasi-experiments, and single-case studies. John Wiley & Sons.

Johnson, P. O., & Neyman, J. (1936). Tests of certain linear hypotheses and their application to some educational problems. Statistical Research Memoirs, 1, 57-93.

Johnson, P. O., & Fey, L. C. (1950). The Johnson-Neyman technique, its theory, and application. Psychometrika, 15, 349-367.

Pedhazur, E. J. (1997). Multiple regression in behavioral research: Explanation and prediction. (3rd ed.). Wadsworth Thomson Learning

Rast, P., Rush, J., Piccinin, A. M., & Hofer, S. M. (2014). The identification of regions of significance in the effect of multimorbidity on depressive symptoms using longitudinal data: An application of the Johnson-Neyman technique. Gerontology, 60, 274-281.

Examples

head(data_Cohen_Aiken_West_2003_7)

CAW_7 <- 
MODERATED_REGRESSION(data=data_Cohen_Aiken_West_2003_7, DV='yendu',
                     IV='xage',IV_range='tumble',
                     MOD='zexer', MOD_levels='quantiles', 
                     quantiles_IV=c(.1, .9), quantiles_MOD=c(.25, .5, .75),
                     plot_type = 'interaction') 

REGIONS_OF_SIGNIFICANCE(model=CAW_7) 

head(data_Bauer_Curran_2005)

HSBmod <-nlme::lme(MathAch ~ Sector + CSES + CSES:Sector,
                   data = data_Bauer_Curran_2005, 
                   random = ~1 + CSES|School, method = "ML") 
summary(HSBmod)

REGIONS_OF_SIGNIFICANCE(model=HSBmod,  
                        plot_title='Johnson-Neyman Regions of Significance', 
                        Xaxis_label='Child SES',
                        Yaxis_label='Slopes of School Sector on Math achievement')  
                        

# moderated regression	-- with numeric values for IV_range & MOD_levels='AikenWest'       
mharsh_agg <- 
  MODERATED_REGRESSION(data=data_OConnor_Dvorak_2001, DV='Aggressive_Behavior',
                       IV='Maternal_Harshness', IV_range=c(1,7.7), 
                       MOD='Resiliency', MOD_levels='AikenWest', 
                       quantiles_IV=c(.1, .9), quantiles_MOD=c(.25, .5, .75),
                       center = FALSE, 
                       plot_type = 'interaction', 
                       DV_range = c(1,6), 
                       Xaxis_label='Maternal Harshness', 
                       Yaxis_label='Adolescent Aggressive Behavior', 
                       legend_label='Resiliency') 

REGIONS_OF_SIGNIFICANCE(model=mharsh_agg,  
                        plot_title='Johnson-Neyman Regions of Significance', 
                        Xaxis_label='Resiliency', 
                        Yaxis_label='Slopes of Maternal Harshness on Aggressive Behavior')