R: Variance of spell durations in individual sequences

seqivardur {TraMineR} | R Documentation

## Variance of spell durations in individual sequences

### Description

Variance of spell durations of individual state sequences.

### Usage

    seqivardur(seqdata, type=1, with.missing=FALSE)

    ## S3 method for class 'seqivardur'
    print(x, stat='var', ...)

### Arguments

`seqdata` | a state sequence object (`stslist`) as returned by `seqdef`.
`type` | either 1 or 2. The default `type=1` ignores non visited states. Type 2 takes into account the 0-time spent in non-visited states (see Details).
`with.missing` | logical: should non-void missing values be treated as a regular state? If `FALSE` (default) missing values are ignored.
`x` | an outcome of `seqivardur`.
`stat` | string or vector of strings. Duration statistic to be printed. Either `'mean'` (mean duration), `'std'` (standard deviation), `'var'` (variance), `'vmax'` (maximum variance for number of spells), or `'all'`. Default is `'var'`.
`...` | further arguments such as `digits` passed to the next `print` method.

### Details

The returned variance is a population variance, i.e. the sum of squares divided by the number of terms.

When `type=1`, this is the variance of the observed spells in the sequence. When `type=2`, in addition to the observed spells one spell of length 0 is considered for each non-visited state. The mean duration is computed the same way.

### Value

A numeric vector with the variance of spell duration of each sequence.

The returned object has two attributes:

`vmax` | the maximum value that the variance of each sequence could reach given its number of spells.
`meand` | the mean spell duration of each sequence.

### Author(s)

Gilbert Ritschard

### References

Ritschard, Gilbert (2021) Measuring the nature of state sequences, Sociological Methods and Research, forthcoming.

### See Also

`seqdur`, `seqindic`

### Examples

    sq.dat <- c('AAAA','AAAC','ABC','ABAA','AC')
    sq <- seqdef(seqdecomp(sq.dat, sep=''), right=NA)

    seqivardur(sq, type=1)
    seqivardur(sq, type=1, with.missing=TRUE)
    vd2 <- seqivardur(sq, type=2)
    print(vd2, stat='all')
    vd2m <- seqivardur(sq, type=2, with.missing=TRUE)
    print(vd2m, stat=c('var','vmax'))

[Package TraMineR version 2.2-2 Index]