Meta- analysis Flashcards
How do we define a meta analysis?
Meta-analysis means analysis of analyses and is a way of using results from different studies, about the same issue, and studying them as a whole to look for an overall picture about the area of study.
It is more a technique of an analysis than a research method.
If a number of studies separately find the same answer, and then those studies are analysed together (a meta-analysis) then that answer becomes stronger as the studies support one another.
A meta-analysis can also adjudicate where studies find different answers. For example, if one study finds that pre-trial publicity does not have an effect on jury decision making and other studies have found the opposite, that might something worthy of a meta-analysis.
Meta- analysis uses secondary date, what is secondary data? And give an example?
Information that was collected for a purpose other than the current one.
e.g. government statistics, results from a different experiment.
What are the 6 steps meta- analysis?
- Define the reseach question
- Perform the literature search
- Select the studies
- Extract the data
- Analyse the data
- Report the results
What happens in the Define the research question in meta analysis?
Similar to any research study, a meta-analysis begins with a research question.
Meta-analysis can be used in any situation where the goal is to summarize quantitative findings from empirical studies.
It can be used to examine different types of effects, including prevalence rates (e.g., percentage of rape survivors with depression), growth rates (e.g., changes in phobic behaviours from pre-treatment to post-treatment), group differences (e.g., comparison of treatment and placebo groups on depression), and associations between variables (e.g., correlation between depression and self-esteem).
While selecting a research question, researchers should think about the size of the literature base and select a manageable topic. At the same time, they should make sure the number of existing studies is large enough to warrant a meta-analysis.
What happens in the Perfrom the literature search in meta- analysis?
The next step is to identify, retrieve, and review published and unpublished studies. The goal is to be exhaustive; however, being too broad can result in an overwhelming number of studies to review.
Online databases, such as PsycINFO and PubMed, compile millions of searchable records, including peer-reviewed journals, books, and dissertations.
In addition, through these electronic databases, researchers can access the full text of many of the records. It is important that researchers carefully choose search terms and databases, because these decisions impact the breadth of the review. Researchers who aren’t familiar with the research topic should consult with an expert.
What happens in the select the studies part in meta analysis?
First, read the titles and abstracts of all relevant searched papers. But before you do so, set up a scheme where you will decide that you will select and reject articles for your meta-analysis.
After you have run through this step and have identified a certain number of studies which must be included in the meta-analysis, obtain their full texts. Then read the full text once more and conduct this rejection exercise and note the numbers. As may be expected, you will reject fewer articles in this round.
Then, read the full text and hand search the reference lists of these articles to widen your research. This step is critical. Often, in this step, you will find out sources that you must search, or identify authors whose work you must read to get a full list of all works and researches that have been conducted on this topic. Do not skip this step. In this step, you will note that some authors feature prominently, and some research groups surface; take a note of them; you may have to write to a few authors to identify if they have published more research.
What happens in the extract the data part in meta analyis?
Once you know that you have a set of studies that you will work with, you will need to work with, you will now need to abstract data from them for your study
The next step in the process isextracting thedatafor analysis and synthesis. Creating aspreadsheet, table, or some other form torecordthe information makes this part of the processeasier. The extracted data depends on theresearch question, but it mayincludeinformation such as sample size, patientcharacteristics, length of study, and a statisticalmeasure, such as confidence interval,odds ratio,risks ratio, mean difference, or hazardratio.
What happens in analyse the data part of meta analysis?
Once you have organized it, your next step istoanalysethe data using statistical software.
Researchers calculate an effect size for each eligible study. The effect size is the key component of a meta-analysis because itencodes the results in a numeric value that can then be aggregated.
Aforest plotwill allow you tocomparestatistical differences between groups.
What are some strengths in meta- analysis?
Increases the validity of the conclusions drawn as they’re based on a wider sample of participants.
Often, studies in a review produce contradictory results (e.g. some studies may find no effect, some a small effect, others a larger effect). A meta-analysis allows us to reach an overall conclusion by having a statistic to represent the findings of different studies.
Increases the validity of the conclusions drawn as they’re based on a wider sample of participants.
Often, studies in a review produce contradictory results (e.g. some studies may find no effect, some a small effect, others a larger effect). A meta-analysis allows us to reach an overall conclusion by having a statistic to represent the findings of different studies
What are some weaknesses of meta analysis?
Research designs in stidies can vary so they are not truly comparable
What is publication bias?
The problem here is that “positive” studies are more likely to go to print.
What is search bias?
The search for studies can produce unintentionally biased results. This includes using an incomplete set of keywords or varying strategies to search databases. Also, the search engine used can be a factor.
What is selection bias?
Researchers must clearly define criteria for choosing from the long list of potential studies to be included in the meta-analysis to ensure unbiased results
