PDIFF: Pairwise Difference

In sasLM: 'SAS' Linear Model

Pairwise Difference

Description

Estimates pairwise differences by a common method.

Usage

  PDIFF(Formula, Data, Term, conf.level=0.95, adj="lsd", ref, PLOT=FALSE, 
        reverse=FALSE, ...)

Arguments

Formula	a conventional formula for a linear model
Data	a data.frame to be analyzed
Term	a factor name to be estimated
conf.level	confidence level of the confidence interval
adj	"lsd", "tukey", "scheffe", "bon", "duncan", or "dunnett" to adjust the p-value and confidence limit
ref	reference or control level for the Dunnett test. If missing, the first level is used, as SAS does.
PLOT	whether to plot the diffogram
reverse	reverse A - B to B - A
...	arguments to be passed to plot

Details

It corresponds to the PDIFF option of SAS PROC GLM.

Value

Returns a table of expectations, t values and p-values. Output columns may vary according to the adjustment option.

Estimate	point estimate of the input linear contrast
Lower CL	lower confidence limit
Upper CL	upper confidence limit
Std. Error	standard error of the point estimate
t value	value for the t distribution
Df	degrees of freedom
Pr(>|t|)	probability of a larger absolute t value from the t distribution with the residual's degrees of freedom

Author(s)

Kyun-Seop Bae [e-mail]

See Also

LSM, Diffogram

Examples

  PDIFF(uptake ~ Type*Treatment + as.factor(conc), CO2, "as.factor(conc)")
  PDIFF(uptake ~ Type*Treatment + as.factor(conc), CO2, "as.factor(conc)", adj="tukey")

sasLM documentation built on June 15, 2026, 9:07 a.m.