# Responsiveness

Command: | Statistics Agreement & responsiveness Responsiveness |

## Description

Allows to calculate various indices for responsiveness, which is the ability to detect any change.

## Required input

**1**: the variables for a 1^{st}and 2^{nd}measurement^{st}and 2^{nd}measurement.**Filter**: an optional filter to include only a selected subgroup of subjects (rows).**Options****Paired data**: select this option when the variables for 1^{st}and 2^{nd}measurements contain paired data (measurements are repeated on the same subjects). If the 2 measurements are independent, unselect this option.**Calculate differences as**: option to calculate differences as 1st minus 2nd measurement (default is 2nd minus 1st).**Advanced**: the confidence intervals for the different indices of responsiveness are estimated using the bias-corrected and accelerated (BC_{a}) bootstrap (Efron, 1987; Efron & Tibshirani, 1993). Click the button for bootstrapping options such as number of replications and random-number seed.

## Results

### Summary statistics

- The sample size, mean, variance and standard deviation of the 1
^{st}and 2^{nd}measurement.

### Difference

- The average difference between the two measurements with the pooled standard deviation and (in case of paired observations) the standard deviation of the paired differences.

### Indices of responsiveness

**Effect size (ES) using baseline SD**: this is the average difference divided by the standard deviation of the 1^{st}measurement (this is Glass' Δ).**Effect size (ES) using pooled SD**: this is the average difference divided by the pooled standard deviation of both measurements (this is Cohen's*d*).**Standardized response mean (SRM)**: this is the average difference divided by the standard deviation of the differences between the paired measurements.

## Literature

- Efron B (1987) Better Bootstrap Confidence Intervals. Journal of the American Statistical Association 82:171-185.
- Efron B, Tibshirani RJ (1993) An introduction to the Bootstrap. Chapman & Hall/CRC.
- Husted JA, Cook RJ, Farewell VT, Gladman DD (2000) Methods for assessing responsiveness: a critical review and recommendations. Journal of Clinical Epidemiology 53:459-168.
- Norman GR, Wyrwich KW, Patrick DL (2007) The mathematical relationship among different forms of responsiveness coefficients. Quality of Life Research 16:815-822.