sla (version 0.1)

eqslo: Equivalent Slopes Data Frame - eqslo

Description

A small (input) data frame comprised of three columns in specific order: (1) Factor (group) variable at two levels, (2) x; a numerical regressor vector, and (3) y; a numerical criterion vector. The data are contrived to yield statistically equivalent slopes but statistically different intercepts.

Usage

data("eqslo")

Format

A data frame with 10 observations on the following 3 variables.

Details

For the general two-group, straight line ANCOVA problem, the full model fits four parameters - two intercepts and two slopes, one intercept and one slope for each of the two groups. One of the reduced models fits three parameters - two separate intercepts, and a single, common slope. The data in the eqslo data frame are contrived to yield statistically equivalent (parallel) slopes and statistically different intercepts.

References

Dalgaard P (2002) Introductory Statistics with R. Springer. Draper NR and Smith H (1998) Applied Regression Analysis. 3rd ed. Wiley. Fox J (2008) Applied Regression Analysis and General Linear Models, 2nd ed. Sage. Venables WN and Ripley BD (2002) Modern Applied Statistics with S. 4th ed. Springer.

Examples

data(eqslo)
str(eqslo)
eqsloObj <- sla(eqslo)
plot(eqsloObj, mod = "A")