R: Recover the "discoverability coefficient".

getTheta {chords}

R Documentation

Recover the "discoverability coefficient".

Description

Estimates the effect of the degree on the rate of sampling. Also known as the "coefficient of discoverability" in the oil-discovery literature [2]. Formally, we estimate \theta and \beta_0 assuming that \beta_k:= \beta_0 * k^\theta.

Usage

  getTheta(rds.object, bin=1, robust=TRUE)

Arguments

`rds.object`	A `rds-object` with a `estimates` component as returned by `Estimate.b.k`
`bin`	Bin degree counts. See Note.
`robust`	Should `\beta_0` and `\theta` be recovered from `\beta_k` using a robust method (default) or not.

Value

A list including the following components:

`log.beta_0`	The log of `\beta_0` in `\beta_k:= \beta_0 * k^\theta`.
`theta`	`\theta` in `\beta_k:= \beta_0 * k^\theta`.

Note

If degree counts have been binned by initializeRdsObject (for variance reduction), the same value has to be supplied to getTheta for correct estimation.

References

[1] Berchenko, Yakir, Jonathan Rosenblatt, and Simon D. W. Frost. "Modeling and Analyzing Respondent Driven Sampling as a Counting Process."" arXiv:1304.3505. HTTP://arXiv.org/abs/1304.3505. [2] Bloomfield, P., K.S. Deffeyes, B. Silverman, G.S. Watson, Y. Benjamini, and R.A. Stine. Volume and Area of Oil Fields and Their Impact on Order of Discovery, 1980. http://www.osti.gov/scitech/servlets/purl/6037591.