v0.2.6 created on Nov. 18, 2018
  (1) added reference in 'Description' field of 'DESCRIPTION' file
  (2) remove \dontrun{} and donttest{} and revised examples so that each example can be executed in < 5 sec
v0.2.5 created on Sept 2, 2018
  (1) replace Weiliang Qiu's email address from stwxq@channing.harvard.edu to
      weiliang.qiu@gmail.com
  (2) use 'Authors@R' in DESCRIPTION file
v0.2.4 created on Sept 2, 2018
  (1) double check the package use the latest version of R 3.5.1
v0.2.3 created on June 21, 2018
  (1) set the number of clusters as 50 in examples
v0.2.2 created on June 13, 2018
  (1) remove row names after create data frame in simulated data
  (2) output regression coefficient of GEE in the 'getScore' function
  (3) write a power calculation function so that the user can input pilot data to obtain parameter estimates

v0.2.1 created on March 29, 2018
  (1) simplify the function 'getScore' a little to drop the output 'id'

v0.2.0 created on March 21, 2018
  (1) fixed a typo: 'taht' should be 'that' in 'powerCal.Rd'

v0.1.9 created on March 7, 2018
  (1) change 'sid' to 'cid'
  (2) change 'uid' to 'subuid'
  (3) change 'value' to 'score'

v0.1.8 created on Feb. 28, 2018
  (1) sort simulated data by uid and sid
v0.1.7 created on Feb. 01, 2018
  (1) remove some unrelated intermediate outputs

v0.1.6 created on Dec. 28, 2017
  (1) In 'genSimDataGLMEM', set the default values: beta0=-6
  
v0.1.5 created on May 18, 2017
  (1) remove the input 'theta1' from the function 'powerCal'
  (2) update the mannual for 'powerCal'
v0.1.4 created on May 3, 2017
  (1) simplify code, e.g. reduce the number of calcuations for ci, di
  (2) renmae 'getFrame' to 'getScore'
  (3) drop some output functions. Keep only functions:
       genSimDataGLMEM, getScore, powerCal, riskPredict, riskPredictDiff

v0.1.3 created on May 3, 2017
  (1) add function 'genSimDataGLMEM'

v0.1.2 created on April 25, 2017
  (1) add summary.riskPredict and summary.riskPredictDiff 
      for 'riskPredict' and 'riskPredictDiff'
  (2) fixed a bug in 'genDat12': in paste statement, "\n" should be
      sep="" 
  (3) add output E.stat.Ha and E.diff.Ha
  (4) revised the construction of 95% CI for eta_c to make sure
      95% CI is within the interval (0, 1)
  (5) use 'cov' instead of 'cor', otherwise for some case,
      corMat in calculation Cov(A1, A2) will not be a correlation matrix

v0.1.1 created on April 13, 2017
  (1) suppress the output of gee
  (2) add 'verbose' input option for 'getFrame'
  (3) output 95% CI
v0.1.0 created on April 12, 2017
  (1) add GEE wrapper function

v0.0.9 created on March 22, 2017
  (1) optimize Tstat.func and genDelta2

v0.0.8 created on Feb. 27, 2017
#  (1) fixed a bug in riskPredict: z = (stat - 0.5)/se.stat
v0.0.7 created on Feb. 23, 2017
  (1) exclude Tstat.func from NAMESPACE

v0.0.6 created on Feb. 23, 2017
  (1) add function 'riskPredict' and 'riskPredictDiff'
  (2) put genDelta inside genDat1 
  (3) put genDelta2 inside genDat12

v0.0.5 created on Feb. 23, 2017
  (1) add manual for genDat1 and genDat12

v0.0.3 created on Feb. 1, 2017
  (1) dropped 'eCDF.func'
  (2) in function 'genDelta', replace "rep=TRUE" by "replace=TRUE"

v0.0.2 created on Feb. 1, 2017
  (1) added "importFrom("stats", "aov", "optim", "pnorm", "qnorm")" to NAMESPACE
  (2) added 'genDelta', 'genDelta2'
