# Math Help - predict future price

1. ## 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

2. 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?

3. 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

5. 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.

6. sorry, the numbers are prices, it is a challenge question from someone nothing more

any reasonable prediction will do

Thanks

7. Originally Posted by isaacm1
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

8. thanks but I need equation , he also mention to use the average of all 10 days , does that help ?

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 $y = -0.0038x+11.425$

10. Thanks, where x is the number of future days ?

11. yep, x=11,12,13,14 for the next 4 values. This result is linear and will tend to zero as $x \rightarrow \infty$

12. Many Thanks,

one question please how you get the -0.0038 value ?

13. 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

14. if my numbers changed I need to know how to get the "b" value (-0.0038)

15. Originally Posted by pickslides
How to find 'b' is in this link my firend.

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