I have a dataset containing values representing monthly sales in hypothetical e-commerce website. First columns contains order of particular month (eplanatory variable) and the second column (dependent variable) is value of sales in this month.

month_order value
    1   2591
    2   2262
    3   2531
    4   2379
    5   2106
    6   2500
    7   2345
    8   2200
    9   2385
    10  2991
    11  2219
    12  2600
    13  3000

Equation of linear regression for this data set is:

f(x) = 27,42x + 2278

Question: Because I would like to make a very simple prediction of sales value in next month and I have no another more suitable eplanatory variable, may I use month_order and predict linear trend? In my case it would be:

f(14) = 27,42 * 15 + 2278 = 2689

is this correct in a theory of a linear regression and can I count it in this way?


1 Answer 1


The only issue here is an assumption violation; i.e. correlated errors. You would probably be better served using autoregressive or moving-average methods rather than a simple linear extrapolation.

  • $\begingroup$ Could you be more specific what particular method I can use? I am not depended on linear regression only, I can use another method if is more suitable. $\endgroup$
    – jnemecz
    Mar 18, 2013 at 14:57
  • $\begingroup$ There are several steps in determining the appropriate model. I would strongly suggest googling "time series analysis" in order to see what is involved. $\endgroup$ Mar 18, 2013 at 16:27

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