glmSLMADS2 {dsBase}R Documentation

glmSLMADS2 called by ds.glmSLMA

Description

This is the second serverside aggregate function called by ds.glmSLMA

Usage

glmSLMADS2(formula, family, offset, weights, dataName)

Arguments

formula

a glm() formula consistent with R syntax eg U~x+y+Z to regress variables U on x,y and Z. Fully specified by <formula> argument in ds.glmSLMA

family

a glm() family consistent with R syntax eg "gaussian", "poisson", "binomial". Fully specified by <family> argument in ds.glmSLMA

offset

an optional variable name (as a character string) identifying an offset vector. Fully specified by <offset> argument in ds.glmSLMA

weights

an optional variable name (as a character sting) identifying a vector of prior regression weights. Fully specified by <weights> argument in ds.glmSLMA

dataName

an optional character string specifying the name of a data.frame object holding the data to be analysed under the specified model. Fully specified by <dataName> argument in ds.glmSLMA

Details

ds.glmSLMA specifies the structure of a generalized linear model (glm) to be fitted separately on each study. The model is first constructed and subject to preliminary disclosure checking by glmSLMADS1. This aggregate function then returns this output to ds.glmSLMA which processes the information and uses it in a call to glmSLMADS2. This call specifies and fits the required glm in each data source. Unlike glmDS2 (called by the more commonly used generalized linear modelling client-side function ds.glm) the requested model is then fitted to completion on the data in each study rather than iteration by iteration on all studies combined. At the end of this SLMA fitting process glmSLMADS2 returns study-specific parameter estimates and standard errors to the client. These can then be pooled using random effects (or fixed effects) meta-analysis - eg using the metafor package. This mode of model fitting may reasonably be called study level meta-analysis (SLMA) although the analysis is based on estimates and standard errors derived from direct analysis of the individual level data in each study rather than from published study summaries (as is often the case with SLMA of clinical trials etc). Furthermore, unlike common approaches to study-level meta-analysis adopted by large multi-study research consortia (eg in the combined analysis of identical genomic markers across multiple studies), the parallel analyses (in every study) under ds.glmSLMA are controlled entirely from one client. This avoids the time-consuming need to ask each study to run its own analyses and the consequent necessity to request additional work from individual studies if the modelling is to be extended to include analyses not subsumed in the original analytic plan. Additional analyses of this nature may, for example, include analyses based on interactions between covariates identified as having significant main effects in the original analysis. From a mathematical perspective, the SLMA approach (using ds.glmSLMA) differs fundamentally from the usual approach using ds.glm in that the latter is mathematically equivalent to placing all individual-level data from all sources in one central warehouse and analysing those data as one combined dataset using the conventional glm() function in R. However, although this may sound to be preferable under all circumstances, the SLMA approach actually offers key inferential advantages when there is marked heterogeneity between sources that cannot simply be corrected with fixed effects each reflecting a study or centre-effect. In particular, fixed effects cannot simply be used in this way when there there is heterogeneity in the effect that is of scientific interest. For more details please see the extensive header for ds.glmSLMA in DataSHIELD and help on the glm function in native R.

Value

All quantitative, Boolean, and character objects required to enable the SLMA pooling of the separate glm models fitted to each study - in particular including the study-specific regression coefficients and their corresponding standard errors. Also, returns warning flags and associated information enabling DataSHIELD to halt analysis and destroy model output from any given study if a disclosure trap is triggered and to inform the user what trap has been triggered.

Author(s)

Burton PR


[Package dsBase version 5.0.0 ]