This package provides methods for obtaining so-called least-squares means for factor combinations in a variety of fitted linear models. It can also compute contrasts or linear combinations of these least-squares means, (several standard contrast families are provided), and in addition can estimate and contrast slopes of trend lines. Popular adjustments for multiple-comparisons are provided, as well as graphical ways of displaying the results.
Almost the entire codebase for lsmeans now resides in the emmeans package (named for the more general term, “estimated marginal means”). lsmeans exists only as a transitional entity for the few remaining packages that depend on it.
Russell V. Lenth (2016) Least-Squares Means: The R Package lsmeans. Journal of Statistical Software, 69(1), 1-33. doi:10.18637/jss.v069.i01
Searle S.R. Speed F.M. Milliken G.A. (1980) Population marginal means in the linear model: An alternative to least squares means. The American Statistician 34(4), 216-221.