x0: X Intercept

In arnima-github/arni: Arni's Toolbox

X Intercept

Description

Evaluate the x intercept and its SE in a simple LM.

Usage

x0(model, se = TRUE)

Arguments

model	a fitted lm or glm of the form y~x.
se	whether to report the standard error.

Value

List containing est (estimated x intercept) and se (standard error), or if se = FALSE a simple number.

Warning

In reality, the uncertainty about the x intercept is asymmetric.

The delta method SE approximation is inaccurate when the slope is close to zero.

Clearly, the x intercept SE is infinity when the slope is not significantly different from zero.

Note

The standard error is evaluated using delta method approximation.

In a logistic glm(family=binomial), the x intercept corresponds to the LD50 inflection point.

arnima-github/arni documentation built on Oct. 28, 2023, 6:18 p.m.