fit2clusters {IdMappingAnalysis} | R Documentation

## Flexible two-cluster mixture fit of a numeric vector

### Description

`fit2clusters` uses an ECM algorithm to fit a two-component mixture model. It is more flexible than mclust in some ways, but it only deals with one-dimensional data.

### Usage

      fit2clusters(Y, Ylabel = "correlation", Ysigsq,
        piStart = c(0.5, 0.5), VStart = c(0.1, 0.1),
        psiStart = c(0, 0.1), NinnerLoop = 1, nReps = 500,
        psi0Constraint, V0Constraint, sameV = FALSE,
        estimatesOnly = TRUE, plotMe = TRUE, testMe = FALSE,
        Ntest = 5000, simPsi = c(0, 0.4), simPi = c(2/3, 1/3),
        simV = c(0.05^2, 0.05^2), simAlpha = 5, simBeta = 400,
        seed, ...)

### Arguments

`Y` | The vector of numbers to fit.
`Ysigsq` | The vector of variance estimates for Y.
`Ylabel` | Label for the Y axis in a density fit figure.
`piStart` | Starting values for the component proportions.
`VStart` | Starting values for the component variances.
`psiStart` | Starting values for the component means
`NinnerLoop` | Number of iterations in the "C" loop of ECM.
`nReps` | Upper limit of number of EM steps.
`psi0Constraint` | If not missing, a fixed value for the first component mean.
`V0Constraint` | If not missing, a fixed value for the first component variance.
`sameV` | If TRUE, the components have the same variance.
`estimatesOnly` | If TRUE, return only the estimates. Otherwise, returns details per observations, and return the estimates as an attribute.
`plotMe` | If TRUE, plot the mixture density and kernel smooth estimates.
`testMe` | If TRUE, run a code test.
`Ntest` | For testing purposes, the number of replications of simulated data.
`simPsi` | For testing purposes, the true means.
`simPi` | For testing purposes, the true proportions
`simV` | For testing purposes, the true variances.
`simAlpha` | For testing purposes, alpha parameter in rgamma for measurement error variance.
`simBeta` | For testing purposes, beta parameter in rgamma for measurement error variance.
`seed` | For testing purposes, random seed.
`...` | Not used; testing roxygen2.

### Details

See the document "ECM_algorithm_for_two_clusters.pdf".

### Value

If estimatesOnly is TRUE, return only the estimates: Otherwise, return a dataframe of details per observations, and return the `estimates` as an attribute. The `estimates` details are:

`pi1` | The probability of the 2nd mixture component
`psi0` | The mean of the first component (psi0Constraint if provided)
`psi1` | The mean of the second component
`Var0` | The variance of the first component (V0Constraint if provided)
`Var1` | The variance of the second component

The `observations` details are:

`Y` | The original observations.
`Ysigsq` | The original measurement variances.
`posteriorOdds` | Posterior odds of being in component 2 of the mixture.
`postProbVar` | Estimated variance of the posterior probability, using the delta method.

[Package IdMappingAnalysis version 1.26.0 Index]