metrica (version 2.1.0)

B0_sma: Intercept of standardized major axis regression (SMA).

Description

It calculates the intercept (B0) for the bivariate linear relationship between predicted and observed values following the SMA regression.

Usage

B0_sma(data = NULL, obs, pred, orientation = "PO", tidy = FALSE, na.rm = TRUE)

Value

an object of class numeric within a list (if tidy = FALSE) or within a data frame (if tidy = TRUE).

Arguments

data

(Optional) argument to call an existing data frame containing the data.

obs

Vector with observed values (numeric).

pred

Vector with predicted values (numeric).

orientation

Argument of class string specifying the axis orientation, PO for predicted vs observed, and OP for observed vs predicted. Default is orientation = "PO".

tidy

Logical operator (TRUE/FALSE) to decide the type of return. TRUE returns a data.frame, FALSE returns a list; Default : FALSE.

na.rm

Logic argument to remove rows with missing values (NA). Default is na_rm = TRUE.

Details

SMA is a symmetric linear regression (invariant results/interpretation to axis orientation) recommended to describe the bivariate scatter instead of OLS regression (classic linear model, which results vary with the axis orientation). For the formula and more details, see online-documentation

References

Warton et al. (2006). Bivariate line-fitting methods for allometry. Biol. Rev. Camb. Philos. Soc. 81, 259–291. tools:::Rd_expr_doi("10.1002/1521-4036(200203)44:2<161::aid-bimj161>3.0.CO;2-N")

Examples

# \donttest{
set.seed(1)
X <- rnorm(n = 100, mean = 0, sd = 10)
Y <- rnorm(n = 100, mean = 0, sd = 9)
B0_sma(obs = X, pred = Y)
# }