Module Components

• Overview

Topics

• Common Parametric and Nonparametric Procedures for Testing Changes over Time
• Quality Improvement: Measurment
• Quality Improvement: Variation
• Run Charts
• Statistical Process Control Charts

NRSG 795: BIOSTATISTICS FOR EVIDENCE-BASED PRACTICE

Module 11: Testing Differences Over Time

Overview

In health care, it is common to measure trends over time. We have learned about techniques to test the significance of change over time in the same individuals using paired t-tests. However, this is only for two periods and we often need to measure the effects for longer than two periods. Moreover, our data may represent different people at every time period (e.g., patient falls on a nursing unit, missed appointments in a clinic). When there are different subjects contributing data for each time period, this can be referred to as trend data and this requires other statistical approaches.

Several approaches to testing the significance of change over time will be examined in the subtopics of this module. We begin with examples applying common parametric and nonparametric statistical procedures that you have already learned and show you how to evaluate changes over time. Then we switch gears and start introducing you to quality improvement concepts. An important component of quality improvement initatives are the types of measures. You will learn how to plot and interpret the variation in the data using Run Charts and Statistical Process Control Charts.

Objectives

At the conclusion of this module, the learner will be able to:

• Evaluate the nature of outcome measures and determine appropriate ways to display trend data.
• Test for changes in trend data using both parametric and non parametric statistical procedures.
• Understand the basic anatomy of charts used in quality improvement (QI): run charts and process control charts.
• Understand some of the basics to interpreting QI charts.

Directions

Complete the required readings, videos, and learning activities under each of the subtopics.