Hi,
Interesting problem.
My take on this (based on my understanding of your problem). You can employ a technique like Shewart chart to determine the behaviour of these variables over time. You can then use time series models to extrapolate these variables into the future and also use shewarts on the forecast result. The forecast will help against the 3 months constraints you have i.e. you can forecast into the future (assuming these variables are quantitative) and you can then determine behaviour of the forecast (as with historic) in addition you have residual analysis (Shewart on the forecast model residual, MAPE etc).
http://support.sas.com/documentation/cdl/en/qcug/63922/HTML/default/viewer.htm#qcug_shewhart_a0000003556.htm
http://support.sas.com/documentation/cdl/en/etsug/66840/HTML/default/viewer.htm#etsug_arima_syntax02.htm
Hope the helps.
Best
Seun Sotuminu
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