summary.mixmeta {mixmeta}

Summarizing mixmeta Models

Description

Print and summary method functions for fitted meta-analytical models represented in objects of class "mixmeta".

Usage

## S3 method for class 'mixmeta'
summary(object, ci.level=0.95, ...)

## S3 method for class 'summary.mixmeta'
print(x, digits=4, report=c("sd","var"), ...)

## S3 method for class 'mixmeta'
print(x, digits=4, ...)

Arguments

object

an object of class "mixmeta" produced by a call to mixmeta.

x

an object of class "mixmeta" or "summary.mixmeta", produced by calls to mixmeta or summary.mixmeta, respectively.

ci.level

a numerical value between 0 and 1, specifying the confidence level for the computation of confidence intervals.

digits

an integer specifying the number of digits to which printed results must be rounded.

report

if standard deviations (sd) or variances (var) must be reported for summarizing the random-effects (co)variance structure.

...

further arguments passed to or from other methods.

Details

The print method function for class "mixmeta" only returns basic information on the fitted model, namely the call, estimated fixed-effects coefficients, dimensions and fit statistics (log-likelihood, AIC, BIC).

The summary method function computes additional statistics and tests, and produces a list object of class "summary.mixmeta". The print method function for this class shows additional information, such as tables reporting the estimates for the fixed and random-effects parts of the model, Cochran Q test for heterogeneity and I-squared.

Value

The summary method function for mixmeta objects produces a list of class "summary.mixmeta". The components of the lists are some of those stored in the related mixmeta object, plus the following:

coefficients

a matrix reporting point estimates, standard errors, z statistics and related p-values of the test, and confidence intervals for the kp fixed-effects coefficients. Note this is different than the component with the same name stored in mixmeta objects, simply reporting the point estimates (see mixmetaObject).

AIC

the value of the Akaike information criterion for the fitted mixmeta model, obtained through a call to AIC.

BIC

the value of the Bayesian information criterion for the fitted mixmeta model, obtained through a call to BIC.

corFixed

the kp \times kp correlation matrix of the fixed-effects coefficients, obtained from the (co)variance matrix vcov (see mixmetaObject and vcov).

corRandom

the kq \times kq correlation matrix of the random effects, obtained from the random-effects (co)variance matrix Psi, or a list of multiple matrices for multilevel models. See mixmetaObject.

qstat

results from the Cochran Q test for heterogeneity, namely a list corresponding to a qtest.mixmeta object without its class, obtained through qtest.

i2stat

I-squared statistic for the meta-analytical model.

ci.level

the confidence level used for defining the confidence intervals for the estimates of the fixed-effects coefficients.

As usual, the print method functions for classes "mixmeta" and "summary.mixmeta" do not return any value.

Author(s)

Antonio Gasparrini <[e-mail]> and Francesco Sera <[e-mail]>

References

Sera F, Armstrong B, Blangiardo M, Gasparrini A (2019). An extended mixed-effects framework for meta-analysis.Statistics in Medicine. 2019;38(29):5429-5444. [Freely available here].

See Also

See mixmeta and mixmetaObject.

Examples

# RUN THE MODEL
model <- mixmeta(cbind(PD,AL) ~ pubyear, S=berkey98[5:7], data=berkey98)

# SIMPLE PRINT
model

# DEFINE DIGITS
print(model, digit=2)

# SUMMARY WITH 80TH CONFIDENCE INTERVALS
summary(model, ci.level=0.80)

# REPORT RANDOM EFFECTS IN TERMS OF VARIANCES (USE print)
print(summary(model), report="var")