MATH question, PLEASE HELP!

[Superwormy]

Ok, I feel really stupid, I'm frickin in college and I can't remember how to do this super simple math stuff.

You have an graph, X axis has time, Y axis has a quanity.


You have a bunch of example data. Predict tommarows quanity based on todays. How do I do this? Hints? Even if someone could just tell me what I'm looking for I could search google for it.

 

[PsychoAndy]

wouldnt you average the values and then plot them?

 

[Woodie]

Plot all the data on the chart (time, reading).

Now, look at the dots on the graph. If they're in (or close to) a straight line, then draw a line, and see where it would intersect on the next day.

There is a mathematical (statistical) way to doing this, IIRC "Least Squares", which calculates the best line to match your data.

 

[Ameesh]

you are in college and you cant do this?!?!?! damn are you a retard?!

this thread is sad

 

[JayHu]

your term on google: extrapolation
whether it be linear or otherwise, I believe that would be the word you're looking for.

 

[Alphathree33]

It depends if you're doing it graphically or mathematically (i.e. approximately or accurately) and the nature of the function...

Let's say you're doing it graphically... if it is linear then just draw a line of best fit through the points that you have, look at the time you would like to predict on the x-axis and trace it up to your line of best fit and then over to the y-axis. There's your prediction.

If it's non-linear then call your function y = kx^n (usable if it goes through the origin and looks like some sort of curve, for example a quadratic)

Now change your axes to log y and log x and graph,..

log y = n log x + k (I just took the log of both sides of the original equation I gave you)

You SHOULD get a line. Remember, you're graphing log x - log y not just x and y.

The slope of that line is n and the y intercept is k (graphically determine these). Slope is rise divided by run (make a right-triangle between any two points on the line and measure its two shortest sides)

Now go back to your original function and you will know the k and n in y = k x ^ n. Sub those in.

Now pick x ("tomorrow") and sub in... you will get y. Again, your prediction.

 

[Alphathree33]

I hate it when I kill threads.

 

[bmacd]

Originally posted by: Alphathree33
I hate it when I kill threads.

kill??? you just saved his ass.

-=bmacd=-

 

[Ameesh]

Originally posted by: bmacd

Originally posted by: Alphathree33
I hate it when I kill threads.

kill??? you just saved his ass.

-=bmacd=-

this guy should be ashamed!