A Hỏi & Đáp | Thực Hiện Phân Tích Gộp Với R - Bookdown

A.1 Chapter 1: Introduction

1. How can meta-analysis be defined? What differentiates a meta-analysis from other types of literature reviews?

Meta-analysis can be defined as an analysis of analyses (definition by Glass). In contrast to other types of (systematic) reviews, meta-analysis aims to synthesize evidence in a quantitative way. Usually, the goal is to derive a numerical estimate that describes a clearly circumscribed research field as a whole.

2. Can you name one of the founding mothers and fathers of meta-analysis? What achievement can be attributed to her or him?

Karl Pearson: combination of typhoid inoculation data across the British Empire; Ronald Fisher: approaches to synthesize data of agricultural research studies; Mary Smith and Gene Glass: coined the term “meta-analysis”, first meta-analysis of psychotherapy trials; John Hunter and Frank Schmidt: meta-analysis with correction of measurement artifacts (psychometric meta-analysis); Rebecca DerSimonian and Nan Laird: method to calculate random-effects model meta-analyses; Peter Elwood and Archie Cochrane: pioneer meta-analysis in medicine.

3. Name three common problems of meta-analyses and describe them in one or two sentences.

“Apples and Oranges”: studies are too different to be synthesized; “Garbage In, Garbage Out”: invalid evidence is only reproduced by meta-analyses; “File Drawer”: negative results are not published, leading to biased findings in meta-analyses; “Researcher Agenda”: researchers can tweak meta-analyses to prove what they want to prove.

4. Name qualities that define a good research question for a meta-analysis.

FINER: feasible, interesting, novel, ethical, relevant; PICO: clearly defined population, intervention/exposure, control group/comparison, and analyzed outcome.

5. Have a look again at the eligibility criteria of the meta-analysis on sleep interventions in college students (end of Chapter 1.4.1). Can you extract the PICO from the inclusion and exclusion criteria of this study?

Population: tertiary education students; Intervention: sleep-focused psychological interventions; Comparison: passive control condition; Outcome: sleep disturbance, as measured by standardized symptom measures.

6. Name a few important sources that can be used to search studies.

Review articles, references in studies, “forward search” (searching for studies that have cited a relevant article), searching relevant journals, bibliographic database search.

7. Describe the difference between “study quality” and “risk of bias” in one or two sentences.

A study can fulfill all study quality criteria that are considered important in a research field and still have a high risk of bias (e.g. because bias is difficult to avoid for this type of study or research topic).