Meta Analysis
Meta analysis is a statistical method that combines similar seperate studies. In meta analysis, we combine an effect size which obtaining from the raw data. The goal of combining the results is obtain more powerful overall effect.
This tool can help you to examine meta analysis! Besides meta analysis, this web tool also includes an effect size calculator, plots for meta analysis and cumulative meta analysis.
There are sample datasets to understand how working this web application is.
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Description
This dataset includes 13 studies on the effectiveness of the Bacillus Calmette-Guerin (BCG) vaccine for preventing tuberculosis (see van Houwelingen, Arends, & Stijnen (2002) for details).
A list of data with the following structure:
No Number of the trials
Author Authors of the original studies
Year Year of the publication
tpos Vaccinated group with disease
tneg Vaccinated group without disease
ttotal Vaccinated group total
cpos Not vaccinated group with disease
cneg Not vaccinated group without disease
ctotal Not vaccinated group total
Ablat Geographic latitude of the place where the study was done
Alloc Method of treatment allocation
References
Berkey, C. S., Hoaglin, D. C., Mosteller, F., & Colditz, G. A. (1995). A random-effects regression model for meta-analysis. Statistics in Medicine, 14(4), 395–411.
Colditz, G. A., Brewer, T. F., Berkey, C. S., Wilson, M. E., Burdick, E., Fineberg, H. V., et al. (1994). Efficacy of BCG vaccine in the prevention of tuberculosis: Meta-analysis of the published literature. Journal of the American Medical Association, 271(9), 698–702.
Description
Results from 9 studies on the length of the hospital stay of stroke patients under specialized care and under conventional/routine (non-specialist) care.
Details
The 9 studies provide data in terms of the mean length of the hospital stay (in days) of stroke patients under specialized care and under conventional/routine (non-specialist) care. The goal of the meta-analysis was to examine the hypothesis whether specialist stroke unit care will result in a shorter length of hospitalization compared to routine management.
The data frame contains the following columns:
No study number
Study source of data
n1i number of patients under specialized care
m1i mean length of stay (in days) under specialized care
sd1i standard deviation of the length of stay under specialized care
n2i number of patients under routine care
m2i mean length of stay (in days) under routine care
sd2i standard deviation of the length of stay under routine care
Source
Normand, S. T. (1999). Meta-analysis: Formulating, evaluating, combining, and reporting. Statistics in Medicine, 18, 321–359.
Description
Results from 19 studies examining how teachers expectations about their pupils can influence actual IQ levels.
DetailsIn the so-called ‘Pygmalion study’ (Rosenthal & Jacobson, 1968), “all of the predominantly poor children in the so-called Oak elementary school were administered a test pretentiously labeled the ‘Harvard Test of Inflected Acquisition.’ After explaining that this newly designed instrument had identified those children most likely to show dramatic intellectual growth during the coming year, the experimenters gave the names of these ‘bloomers’ to the teachers. In truth, the test was a traditional IQ test and the ‘bloomers’ were a randomly selected 20% of the student population. After retesting the children 8 months later, the experimenters reported that those predicted to bloom had in fact gained significantly more in total IQ (nearly 4 points) and reasoning IQ (7 points) than the control group children. Further, at the end of the study, the teachers rated the experimental children as intellectually more curious, happier, better adjusted, and less in need of approval than their control group peers” (Raudenbush, 1984).
In the following years, a series of studies were conducted attempting to replicate this rather controversial finding. However, the great majority of those studies were unable to demonstrate a statistically significant difference between the two experimental groups in terms of IQ scores. Raudenbush (1984) conducted a meta-analysis based on 19 such studies to further examine the evidence for the existence of the ‘Pygmalion effect’. The dataset includes the results from these studies.
The effect size measure used for the meta-analysis was the standardized mean difference (yi), with positive values indicating that the supposed ‘bloomers’ had, on average, higher IQ scores than those in the control group. The weeks variable indicates the number of weeks of prior contact between teachers and students before the expectancy induction. Testing was done either in a group setting or individually, which is indicated by the setting variable. Finally, the tester variable indicates whether the test administrators were either aware or blind to the researcher-provided designations of the childrens intellectual potential.
The data in this dataset were obtained from Raudenbush and Bryk (1985) with information on the setting and tester variables extracted from Raudenbush (1984).
The data frame contains the following columns:
No study number
Author study author(s)
Year publication year
weeks weeks of contact prior to expectancy induction
setting whether tests were group or individually administered
tester whether test administrator was aware or blind
n1i sample size of experimental group
n2i sample size of control group
yi standardized mean difference
vi corresponding sampling variance
Source
Raudenbush, S. W. (1984). Magnitude of teacher expectancy effects on pupil IQ as a function of the credibility of expectancy induction: A synthesis of findings from 18 experiments. Journal of Educational Psychology, 76, 85–97.
Raudenbush, S. W., & Bryk, A. S. (1985). Empirical Bayes meta-analysis. Journal of Educational Statistics, 10, 75–98.
Description
Results from 160 studies on the correlation between employment interview assessments and job performance.
Details
The 160 studies provide data in terms of the correlation between employment interview performance and actual job performance. In addition, the interview type and the interview structure are indicated.
McDaniel et al. (1994) describe the interview type and structure variables as follows. "Questions in situational interviews [...] focus on the individuals ability to project what his or her behavior would be in a given situation. [...] Job-related interviews are those in which the interviewer is a personnel officer or hiring authority and the questions attempt to assess past behaviors and job-related information, but most questions are not considered situational. Psychological interviews are conducted by a psychologist, and the questions are intended to assess personal traits, such as dependability." In structured interviews, "the questions and acceptable responses were specified in advance and the responses were rated for appropriateness of content. [...] Unstructured interviews gather applicant information in a less systematic manner than do structured interviews. Although the questions may be specified in advance, they usually are not, and there is seldom a formalized scoring guide. Also, all persons being interviewed are not typically asked the same questions."
The goal of the meta-analysis was to examine the overall criterion-related validity of employment interviews and to examine whether the validity depends on the type and structure of the interview.
The data in this dataset were obtained from Table A.2 in Rothstein, Sutton, and Borenstein (2005, p. 325-329). Note that the type and struct variables contain some NAs.
The data frame contains the following columns:
No study number
ni sample size of the study
ri observed correlation
type interview type (j = job-related, s = situational, p = psychological)
struct interview structure (u = unstructured, s = structured)
Source
Rothstein, H. R., Sutton, A. J., & Borenstein, M. (Eds.). (2005). Publication bias in meta-analysis: Prevention, assessment, and adjustments. Chichester, England: Wiley.
Description
Results from 9 studies on the reliability of the Center for Epidemiologic Studies Depression (CES-D) Scale administered to children providing care to an elderly parent.
Details
The Center for Epidemiologic Studies Depression (CES-D) Scale is a 20-item questionnaire assessing various symptoms of depression, with each item scored on a 4-point scale. The scale has been used in several studies to examine depressive symptoms in children providing care to an elderly parent. The dataset includes information on the reliability of the scale as measured with Cronbachs alpha in 9 such studies. Also, the gender composition of the children in each sample is indicated.
The data frame contains the following columns:
No study number
Author source of data
ni sample size
mi number of items in the scale
ai observed value of Cronbachs alpha
caregivers gender of the children in the sample
Source
Bonett, D. G. (2010). Varying coefficient meta-analytic methods for alpha reliability. Psychological Methods, 15, 368–385.
Description
Results from 18 studies comparing the risk of catheter-related bloodstream infection when using anti-infective-treated versus standard catheters in the acute care setting.
Details
The use of a central venous catheter may lead to a catheter-related bloodstream infection (CRBSI), which in turn increases the risk of morbidity and mortality. Anti-infective-treated catheters have been developed that are meant to reduce the risk of CRBSIs. Niel-Weise et al. (2007) conducted a meta-analysis of studies comparing infection risk when using anti-infective-treated versus standard catheters in the acute care setting. The results from 18 such studies are included in this dataset.
The data frame contains the following columns:
No study number
Author author
Year publication year
ai number of CRBSIs in patients receiving an anti-infective catheter
n1i number of patients receiving an anti-infective catheter
ci number of CRBSIs in patients receiving a standard catheter
n2i number of patients receiving a standard catheter
Source
Niel-Weise, B. S., Stijnen, T., & van den Broek, P. J. (2007). Anti-infective-treated central venous catheters: A systematic review of randomized controlled trials. Intensive Care Medicine, 33, 2058–2068.
Description
The data frame contains the following columns:
Author Study identifier
type_study Type of study
population Population studied, or source of controls
year Year
country Country of origin
journal Journal of publication
tdeath Deaths on treatment (exposed)
tnodeath Alive on treatment (exposed)
cdeath Deaths not on treatment (unexposed)
cnodeath Alive not on treatment (unexposed)
OR Odds ratio
ORlci Lower 95% CI
ORuci Upper 95% CI
RR Risk Ratio
RRlci Lower 95% CI
RRuci Upper 95% CI
tsample Number treated (exposed)
tmean Mean in treated (exposed)
tsd Standard deviation in treated (exposed)
csample Number not treated (unexposed)
cmean Mean in untreated (unexposed)
csd Standard deviation in untreated (unexposed)
Source
Ross Harris & Mike Bradburn & Jon Deeks & Roger Harbord & Doug Altman & Thomas Steichen & Jonathan Sterne, 2006. "METAN: Stata module for fixed and random effects meta-analysis," Statistical Software Components S456798, Boston College Department of Economics, revised 23 Sep 2010.
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¹Deleted Studentized Residual