sanon (version 1.2)

contrast: Contrast for Model Parameters

Description

Inference by contrast of parameters in a fitted model.

Usage

contrast(object, C = diag(length(object$b)),
    confint = FALSE, level = 0.95, ...)

  ## S3 method for class 'contrast':
print(x, ...)

Arguments

object,x

an object of class "sanon", usually, a result of a call to sanon.

C

contrast matrix. The number of column should be same as the length of b in outputs of sanon.

confint

logical value for whether the confidence interval is computed (only if C has one row).

level

the confidence level required (only if C has one row).

...

further arguments passed to or from other methods.

Value

• C
  contrast matrix
• Cb
  contrast estimates
• VCb
  variance and covariance matrix of Cb
• se
  standard error of Cb
• level
  confidence level
• UL
  upper confidence limit (only if the number of row of C = 1, otherwise NULL)
• LL
  lower confidence limit (only if the number of row of C = 1, otherwise NULL)
• Q
  test statistic
• df
  degree of freedom
• p
  p-value

Details

This function provide the inference based on contrast after applying the function sanon. The contrast matrix C should be defined by the user. If the the number of row of C = 1, the confidence interval for the estimator is produced.

Examples

##### Example 3.2 Randomized Clinical Trial of Respiratory Disorder #####
data(resp)
P = rbind(rep(0, 4), diag(4), rep(0, 4))
out23 = sanon(cbind(baseline, visit1, visit2, visit3, visit4) ~ grp(treatment, ref="P")
 + strt(center) + strt(sex) + covar(age), data=resp, P=P)

# Homogeneity of the xi_k across the four visits
contrast(out23, C=cbind(diag(3), rep(-1, 3)))

# Comparison between treatments for the average of the xi_k across the 4 visits
contrast(out23, C=matrix(rep(1, 4)/4, ncol=4))