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20070709, 20:56 #1
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Re: Driving a formula from data (2003)
How is the result related to X and Y?

20070709, 21:09 #2
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Re: Driving a formula from data (2003)
Ah... therein lies the question. I don't know what the relationship is. I do know that X represents weight and Y represents speed and the result represents calories burned during training. I was unable to find a formula for calculating this but I did find a table with data already populated. I was hoping Excel could help determine the relationship.

20070709, 21:36 #3
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Re: Driving a formula from data (2003)
In order to do this, you must already have some idea about the type of function  linear, polynomial, exponential, logarithmic, .... You can then use Excel to estimate the parameters for the function. Excel cannot determine the type of function to be used.
As you can see from the chart below, the relation between speed and calories isn't a simple straight line, nor a parabola or something like that.

20070709, 21:46 #4
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Deriving a formula from data (2003)
I have a set of variables, X an Y, and a result for each one. For example (these are not actual numbers, just to illustrate the concept):
X Y Result
1 1 1
3 7 4
5 3 4
and so on.
I would like to derive a formula based on what I have so that I and input my own X and Y and receive the correct result.
Is this possible? Again, the numbers above do not represent the actual data

20070709, 21:49 #5
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Re: Driving a formula from data (2003)
Thanks, Hans. I will continue to seek a formula. Your graph was interesting.

20070709, 22:05 #6
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Re: Driving a formula from data (2003)
It won't be easy to express the relation between speed and calories in a formula. You may have better luck with the relation between weight and calories, but then you'd have to create separate formulas for each speed. In other words, I don't think you'll find a formula using both speed and weight.

20070709, 22:20 #7
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Re: Deriving a formula from data (2003)
I suspect you're right. the calories burned is the calories burned per hour of walking. The premise is (I believe) that with a constant speed, calories burned per mile are directly proportional to weight. Likewise, with a constant weight, calories burned per mile are directly proportional to speed.
I guess I forgot the part about calories per mile instead of total calories burned.

20070709, 22:27 #8
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Re: Driving a formula from data (2003)
Hi Don
This is an interesting question, for me anyway <img src=/S/grin.gif border=0 alt=grin width=15 height=15>. Calories burnt and how is calculated is a pretty simple equation, it just has various coefficients.
The main factors are:
1) Weight
2) Type of Sport
3) Length (distance or time)
A very simplistic equation you may want to try is:
Calories burnt = Sport Coefficient * Weight * Distance
A very basic set of Sport Coefficients could be:
Running =0.79
Cycling= 0.28
Swimming = 2.93
This may assist you in find the coefficient but it is variable and depends on age, gender and is indicative and definitely NOT scientific calibrated.Jerry

20070709, 22:42 #9
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Re: Deriving a formula from data (2003)
The first chart shows it's not that simple...

20070710, 16:25 #10
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Re: Deriving a formula from data (2003)
I need to be more careful about reading my posts before I click "Post It". In my last post, I said "the calories burned is the calories burned per <span style="backgroundcolor: #FFFF00; color: #000000; fontweight: bold">hour</span hi> of walking" when, in fact, I meant "the calories burned is the calories burned per <span style="backgroundcolor: #FFFF00; color: #000000; fontweight: bold">mile</span hi> of walking".
In any case, I have found some interesting formulas I can use. Since they are off topic (Excel wise) I won't post them but will share with anyone who asks.
Thanks to all who responded.

20070710, 20:14 #11
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Re: Deriving a formula from data (2003)
Hi Don
Always nterested to hear what you have to say. Can you PM them to me please? <img src=/S/grin.gif border=0 alt=grin width=15 height=15>Jerry