IVW-class: IVW Class
In MendelianRandomization: Mendelian Randomization Package

IVW-class

R Documentation

IVW Class

Description

An object containing the estimate produced using the inverse-variance weighted (IVW) method as well as various statistics.

Slots

Model: The model used for estimation: random-effects ("random") or fixed-effect ("fixed"). The default option ("default") is to use a fixed-effect model when there are three or fewer genetic variants, and a random-effects model when there are four or more. The (multiplicative) random-effects model allows for heterogeneity between the causal estimates targeted by the genetic variants by allowing over-dispersion in the regression model. Under-dispersion is not permitted (in case of under-dispersion, the residual standard error is set to 1, as in a fixed-effect analysis).
Exposure: The name of the exposure variable.
Outcome: The name of the outcome variable.
Correlation: The matrix of correlations between genetic variants.
Robust: Whether robust regression was used in the regression model relating the genetic associations with the outcome and those with the exposure.
Penalized: Whether weights in the regression model were penalized for variants with heterogeneous causal estimates.
Estimate: The causal point estimate from the inverse-variance weighted method.
StdError: The standard error associated with Estimate.
CILower: The lower bound of the confidence interval for Estimate based on StdError.
CIUpper: The upper bound of the confidence interval for Estimate based on StdError.
Alpha: The significance level used in constructing the confidence interval (default is 0.05).
Pvalue: P-value associated with the causal estimate.
SNPs: The number of SNPs that were used in the calculation.
RSE: The estimated residual standard error from the regression model.
Heter.Stat: Heterogeneity statistic (Cochran's Q statistic) and associated p-value: the null hypothesis is that all genetic variants estimate the same causal parameter; rejection of the null is an indication that one or more variants may be pleiotropic.
Fstat: An approximation of the first-stage F statistic for all variants based on the summarized data.