sla (version 0.1)

eqint: Equivalent Intercepts Data Frame - eqint

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 intercepts but statistically different slopes.

Usage

data("eqint")

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 - a single, common intercept, and two separate slopes. The data in the eqint data frame are contrived to yield statistically equivalent intercepts and statistically different slopes.

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(eqint)
str(eqint)
eqintObj <- sla(eqint)
plot(eqintObj, mod = "A")