nwts2ph {addhazard}

An hypothetical two-phase sampling dataset based on nwtsco dataset from the National Wilms Tumor Study (NWTS)

Description

An hypothetical two-phase sampling dataset based on nwtsco dataset from the National Wilms Tumor Study (NWTS)

Usage

nwts2ph

Format

A data frame with 3915 rows and 15 variables:

We create a hypothetical two-phase sampling (stratified sampling) dataset. In this dataset, only the subjects who have relapses and some of the controls have their samples sent to the central laboratory for more accurate histology examination.

Institutional histology is examined in the local hospital. It is usually available for all the samples. Central histology is more expensive to obtain since the samples have to be sent to the central laboratory and the work requires experienced lab scientists. It is reasonable to assume only some samples were tested for central histology. Following the two-phase sampling design, we selected subjects for central histology measurements based on their outcomes and institutional histology results.

trel

Time to relapse or last date seen (yr), continuous

tsur

Time to death or last date seen (yr), continuous

relaps

Indicator of relapse, 0 = Alive no prior relapse when last seen, 1 = Relapsed after trel years

dead

Indicator of death, 0 = Alive when last seen, 1 = Died after tsur years

study

NWTS study, 3 = NWTS-3, 4 = NWTS-4

stage

Stage of disease, 1=I, 2=II, 3=III, 4=IV

histol

Central Path histology, 0 = Favorable (FH) and the subject is selected into the phase II subsample (in.ph2 = 1), 1 = Unfavorable (UH) and the subject is selected into the phase II subsample (in.ph2 = 1), NA = subject is NOT selected into the phase II subsample (in.ph2 = 1)

instit

Institutional histology, 0 = Favorable (FH), 1 = Unfavorable (UH)

age

Age at diagnosis (yr), continuous

yr

Year of diagnosis, calendar year

specwgt

Weight of tumor bearing specimen, in grams (continuous)

tumdiam

Diameter of tumor, in centimeters (continuous)

strt

Strata, 1 = Unfavorable Institutional histology and no relapse, 2 = favorable Institutional histology and no relapse, 3 = relapse

Pi

Sampling probability, 0.5 for strata =1, 0.9 for strata = 2, 0.9 for strata = 3

in.ph2

Phase II membership, 1 = selected into the phase II subsample, 0 = not selected into the phase II subsample

Source

This dataset was created based on nwtsco dataset from the National Wilms Tumor Study (NWTS)