Description Usage Arguments Value Note

View source: R/GenerateDataForDemonstration.r

Simulates a dataset with two functional covariates, four subject-level scalar covariates, and a binary outcome.

1 2 3 4 5 6 7 8 9 10 | ```
generate.data.for.demonstration(
nsub = 400,
b0.true = -5,
b1.true = 0,
b2.true = +1,
b3.true = -1,
b4.true = +1,
nobs = 500,
observe.rate = 0.1
)
``` |

`nsub` |
The number of subjects in the simulated dataset. |

`b0.true` |
The true value of the intercept. |

`b1.true` |
The true value of the first covariate. |

`b2.true` |
The true value of the second covariate. |

`b3.true` |
The true value of the third covariate. |

`b4.true` |
The true value of the fourth covariate. |

`nobs` |
The total number of possible observation times. |

`observe.rate` |
The average proportion of those possible times at which any given subject is observed. |

Returns a `data.frame`

representing `nobs`

measurements for each subject. The rows of this `data.frame`

tell the values of two time-varying covariates on a dense grid
of `nobs`

observation times. It also contains an
`id`

variable, four subject-level covariates
(`s1`

, ..., `s4`

) and one subject-level
response (`y`

), which are replicated for each observation.
For each observation, there is also its observation
time `time`

, there are both the smooth latent value of the covariates
(`true.x1`

and `true.x2`

) and
versions observed with error (`x1`

and `x2`

), and there are
also the local values of the functional regression coefficients
(`true.betafn1`

and `true.betafn2`

). Lastly,
each row has a random value for `include.in.subsample`

,
telling whether it should be considered as an observed data
point (versus an unobserved moment in the simulated subject's life).
`include.in.subsample`

is simply generated as a Bernoulli random variable with
success probability `observe.rate`

.

`nobs`

is the number of simulated data rows per
simulated subject. It
should be selected to be large because `x`

covariates are conceptually
supposed to be smooth functions of time. However, in the
simulated data analyses we actually only use a small random
subset of the generated time points, because this is more
realistic for many behavioral and medical science datasets.
Thus, the number of possible observation times per subject
is `nobs`

, and the mean number of actual observation
times per subject is `nobs`

times `observe.rate`

.
This smaller 'observed' dataset can be obtained by
deleting from the dataset those observations having
`include.in.subsample==FALSE`

.

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