Forecasting Function Doesn't Seem to Calculate Correctly
I am trying to forecast purchasing dept items for my company and it appears that the forecasting of my weights are looking flat when trying to determine what to buy and when. Look at how my chart reacts when I forecast. Do you have any thoughts on why this happens?
XLS File: https://drive.google.com/open?id=0B_...UZKbGVnVTF1SjA
Sketch.png
The Forecast function uses linear regression to draw a straight line through the middle of your data (best fit). It will not mimic all the ups and downs of your data.
Try to figure out what's causing all the ups and downs and separate out that data and chart it separately. i.e. if sales are high on Thurs, Friday but steady rest of the week. Chart Thurs - Friday and look for trends.
If the data is seasonal (you're selling ski caps), then separate seriess by season, quarter or month (if you have enough data).
Look for other trending clues, holidays, new marketing ploys, news items (fall out shelters are selling well right now).
Hope that helps
Lastly, you could try to fit a polynomial curve into your data using LINEST but make sure you're not trying to fit a square peg into a round hole.
1. Chart each month
ChemistB
My 2?
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