AB.Ab.aB.ab2 {VGAM} | R Documentation

## The AB-Ab-aB-ab2 Blood Group System

### Description

Estimates the parameter of the the AB-Ab-aB-ab2 blood group system.

### Usage

    AB.Ab.aB.ab2(link = "logit", earg=list(), init.p = NULL)

### Arguments

`link` | Link function applied to `p`. See `Links` for more choices.
`earg` | List. Extra argument for the link. See `earg` in `Links` for general information.
`init.p` | Optional initial value for `p`.

### Details

This one parameter model involves a probability called `p`.

### Value

An object of class `"vglmff"` (see `vglmff-class`). The object is used by modelling functions such as `vglm` and `vgam`.

### Warning

There may be a bug in the `deriv` and `weight` slot of the family function.

### Note

The input can be a 4-column matrix of counts. Alternatively, the input can be a 4-column matrix of proportions (so each row adds to 1) and the `weights` argument is used to specify the total number of counts for each row.

### Author(s)

T. W. Yee

### References

Elandt-Johnson, R. C. (1971) Probability Models and Statistical Methods in Genetics, New York: Wiley.

### See Also

`AA.Aa.aa`, `AB.Ab.aB.ab`, `ABO`, `G1G2G3`, `MNSs`.

### Examples

    # See Elandt-Johnson, pp.430,427
    # Estimated variance is approx 0.0021
    y = cbind(68, 11, 13, 21)
    fit = vglm(y ~ 1, AB.Ab.aB.ab2(link=logit), trace=TRUE, crit="coef")
    fit = vglm(y ~ 1, AB.Ab.aB.ab2(link=cloglog), trace=TRUE, crit="coef")
    Coef(fit)   # Estimated p
    rbind(y, sum(y)*fitted(fit))
    sqrt(diag(vcov(fit)))

[Package VGAM version 0.7-9 Index]