The trial was aimed to evaluate the treatment effect for patients with kidney problem.
The four treatment groups are (variable name- group):

       1= 1alphad2+tums
       2= 1alphad2+renagel
       3= calcitriol+tums
       4= calcitriol+renagel

The main outcome is PTH (hormone). The are three way to measure PTH level (the three variables are: PTH, iPTH and BioPTH).
PTH and other chemistries were measured monthly (protocol schedule was month 0-8)

Bone biopsy was done twice: baseline and at the end of study.  There are many bone parameters. The most important one is BFR_BS.

The investigator was mainly interested to see how PTH, CA and other biochemistries change overtime and the difference among the four groups. 
Another interest is to study the relationship between lab data and bone parameters.