Unstable Path Balance and Power Control

Hi

Could you please axplain to me what could be the cause of Unstable Path balance on a radios and Power Control, Say a radio experiences low or hgh path balance this week and is calibrated and DCR improve after a week or so it comes back again without any one changing anything on the site, Smae setuation for Power control, Sometimes a cell picks more traffic than usual and later on or after a week come back to normal.

Please assist.

Thanking you in Advance.
Rgds
Isaac