Chapter 4: Critically Appraise the Results of an Intervention Research Study

Pre-Test

1. What are the differences between descriptive statistics and inferential statistics?

2. How do you determine if the results of a research study are clinically important?

3. The median income in the United States is $44,000, but the mean income is $60,500. Why are these values different? Which value is likely to best describe incomes in the United States?

4. Why is 0.05 typically chosen as the alpha value in a research study?

5. Which value represents the difference between two treatments in a randomized clinical trial: alpha level, p value, effect size, or number needed to treat?

Introduction

Chapters 3 and 4 support your knowledge and skill development for the third step of evidence based practice (EBP):

STEP 3: Critically appraise the research evidence for applicability and quality

Chapter 3 included parts A, Determining applicability, and B, Determining quality of a research study. This chapter includes parts

C. Interpreting study results and

D. Summarizing the clinical bottom line (Fig. 4.1).

Reading and interpreting study results can be challenging. If you develop a systematic approach to reading through the results of a study, it becomes easier and faster to interpret the study findings. This chapter describes a process for appraising results and guides you through the appraisal, including the interpretation of statistics.

Part C: Interpreting Results of an Intervention Study

Locating and Appraising the Results of a Research Study

Tables have it all! The results of intervention research studies are summarized in tables. A helpful habit to develop is to read through the tables in a paper and reflect on the information contained in them before trying to understand the text in the results section. The title of a table indicates what will be included in the main part of the table. Figure 4.2 illustrates a typical table describing the demographic and clinical characteristics of the study sample for each group.¹

Data are summarized using descriptive statistics. Descriptive statistics give you an overall impression of the typical values for the group as well as the variability within and between the groups.^2,3 First, look at the demographic data. Compare the control and the two training groups on average age, height, weight, and ...