MVIVW-class {MRZero}

MVIVW Class

Description

An object containing the estimates produced using the multivariable 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 names of the exposure variables.

Outcome

The name of the outcome variable.

Robust

Whether robust regression was used in the regression model relating the genetic associations with the outcome and those with the exposure.

Correlation

The matrix of correlations between genetic variants.

Estimate

The causal estimates from the inverse-variance weighted method.

StdError

The standard errors associated with Estimate.

CILower

The lower bounds of the confidence interval for Estimate based on StdError.

CIUpper

The upper bounds 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.

CondFstat

Conditional F statistics: An approximation of the first-stage conditional F statistics for all variants based on the summarized data. This represents the instrument strength for each exposure conditional on other exposures in the model. This is only reported if the sample sizes for the genetic associations with the exposures are provided.