ham (version 1.0.0)

itsEffect: Interrupted time series analysis effects

Description

Calculates effects for intervention and control groups based on interrupted time series models from an assess class object. Within a period (or interruption), the effect that represents the trend during the period is calculated for both groups as well as the difference between the groups. Summary statistics are provided that include the effect sizes, t-statistic, standard errors, p-values, and 95% confidence intervals of the effect sizes. These values are provided for the intervention group, control group (when applicable), and the differences between the two groups (Linden, 2015). These values are automatically generated while running a model in assess.

Usage

itsEffect(model, type)

Value

a data.frame object of ITS effects and summary statistics. Generally run within the assess function.

Arguments

model

an interrupted time series (ITS) model with the "lm" class,

type

analysis type for single or multiple groups and single or multiple time periods. If selected type="sgst", it is single-group single-time; type="sgmt", it is single-group multiple-time; type="mgst", it is multiple-group single-time; and type="mgmt", it is multiple-group multiple-time.

References

Linden, Ariel. (2015). Conducting Interrupted Time-series Analysis for Single- and Multiple-group Comparisons. The Stata Journal, 2015, 15(2), 480-500, https://doi.org/10.1177/1536867X1501500208

Examples

i21 <- assess(formula=survey ~ ., data=hosprog, intervention = "program",topcode =NULL,
int.time="month", regression="none", interrupt=5, its="two", newdata=TRUE, propensity=NULL)
itsEffect(model= i21$ITS, type= "mgst")