Quasars {DTDA} | R Documentation |
Quasars Data
Description
The original dataset studied by Efron and Petrosian (1999) comprised independlently collected quadruplets of the redshift and the apparent magnitude of a quasar object. Due to experiemtnal constraints, the distribution of each luminosity in a log-scale is truncated to a known interval.
Usage
data(Quasars)
Format
A data frame with 210 observations on the following 3 variables.
y (adj lum)
a numeric vector, the log lominosity values.
u (lower)
a numeric vector, lower truncation limits.
v (upper)
a numeric vector, upper truncation limits.
Details
Quadruplets in the original data set studied by Efron and Petrosian (1999) are of the form , where
is the redshift of the ith quasar and
is the apparent magnitude. Due to experimental constraints, the distribution of each luminosity in the log-scale
is truncated to a known interval
, where
represents a transformation which depends on the cosmological model assumed (see Efron
and Petrosian (1999) for details). Quasars with apparent magnitude above
were too dim to yield dependent redshifts, and hence they were excluded from the study. The lower limit
was used to avoid confusion with non quasar stellar objects.
Source
Vahé Petrosian and Bradley Efron.
References
Boyle BJ, Fong R, Shanks, T and Peterson, BA (1990) A catalogue of faint, UV-excess objects. Monograph National Royal Astronomical Society 243, 1-56.
Efron B and Petrosian V (1999) Nonparametric methods for doubly truncated data. Journal of the American Statistical Association 94, 824-834.
Examples
data(Quasars)
str(Quasars)