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Math Help - predict future price

  1. #1
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    predict future price

    Hello,
    I need to get a prediction for 4 days ahead for an item price, I have only the last 10 days prices history of that item.

    what would be the equation to solve this ?

    Thanks
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  2. #2
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    There are many different ways to predict the next 4 values. It can be dependant on many things, what were the previous 10 values you have?
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  3. #3
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    11.4124 , 11.4196 , 11.4289 , 11.4127, 11.4076 , 11.3988 , 11.3821 ,11.3798 , 11.3926 ,11.4025

    of course most accurate method will be better but please post two if possible

    Thanks
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  4. #4
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    any reply ??
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  5. #5
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    Be patient my friend, they are many posters from all different corners of the world on this forum so everyone is on a different time zone, since my last post I have enjoyed some very deep sleep, 8 of the best you could say.

    Looking at your data and considering it is daily I would suggest the next 4 values could be decreasing. There seems to be a peak at the 3rd value and then after the 8th value it increases again. 10 values is a very small set to make a prediction on. There seem to be 2 weekly increases after values 1,2,8 & 9. These could very well be weekends.

    Any more information regarding the nature of the data?
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  6. #6
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    sorry, the numbers are prices, it is a challenge question from someone nothing more

    any reasonable prediction will do

    Thanks
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  7. #7
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    Quote Originally Posted by isaacm1 View Post
    any reasonable prediction will do
    11.4124
    11.4196
    11.4289
    11.4127
    11.4076
    11.3988
    11.3821
    11.3798
    11.3926
    11.4025
    11.38289
    11.37689
    11.37237
    11.37138
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  8. #8
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    thanks but I need equation , he also mention to use the average of all 10 days , does that help ?
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  9. #9
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    For your data

    11.4124
    11.4196
    11.4289
    11.4127
    11.4076
    11.3988
    11.3821
    11.3798
    11.3926
    11.4025


    you could use a linear least squares regression, there are many options. This would give the equation y = -0.0038x+11.425
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  10. #10
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    Thanks, where x is the number of future days ?
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  11. #11
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    yep, x=11,12,13,14 for the next 4 values. This result is linear and will tend to zero as x \rightarrow \infty
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  12. #12
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    Many Thanks,

    one question please how you get the -0.0038 value ?
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  13. #13
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    It is the gradient for y=bx+a from the least squares regression. It is a long a boring explantion but if you really want to know check out

    Least-Squares Line
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  14. #14
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    if my numbers changed I need to know how to get the "b" value (-0.0038)
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  15. #15
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    Quote Originally Posted by pickslides View Post
    How to find 'b' is in this link my firend.
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