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Topic: Kinetics data  (Read 6677 times)

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Offline curiouscat

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Re: Kinetics data
« Reply #15 on: August 27, 2013, 08:30:09 AM »
And here, k1 is y, t is x?

I can rearrange it for k1 = k/t where k is a constant.

y is the dependent variable. x is the independent. c and k are clubbed together constants.

If you even suspected k1 is y you need to revisit fundamentals of curve fitting or regression I think.

Offline Babcock_Hall

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Re: Kinetics data
« Reply #16 on: August 27, 2013, 09:07:57 AM »
Big-Daddy,

In my experience students have a hard time getting the notion that in regression, the parameters (c and k) are what the experimenter is usually most interested in, as opposed to the variables (x and y).  Perhaps you could look at your equation and identify the parameters and the variables.

Offline curiouscat

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Re: Kinetics data
« Reply #17 on: August 27, 2013, 09:43:42 AM »
Big-Daddy,

In my experience students have a hard time getting the notion that in regression, the parameters (c and k) are what the experimenter is usually most interested in, as opposed to the variables (x and y).  Perhaps you could look at your equation and identify the parameters and the variables.

The confusing semantics of "parameters, variables and constants" is another source of misunderstanding.

Offline Babcock_Hall

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Re: Kinetics data
« Reply #18 on: August 27, 2013, 09:50:03 AM »
Can you elaborate on this?  Under normal circumstances the independent variable should have little or no error, but the dependent variable may have error with certain caveats.  Often the experimenter can control the independent variable and measure the dependent variable.  That leaves us with what to call c and k in this example.  Perhaps I should have not used the word parameters (so that things would be less muddled).

Offline curiouscat

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Re: Kinetics data
« Reply #19 on: August 27, 2013, 10:24:17 AM »
Can you elaborate on this?  Under normal circumstances the independent variable should have little or no error, but the dependent variable may have error with certain caveats.  Often the experimenter can control the independent variable and measure the dependent variable.  That leaves us with what to call c and k in this example.  Perhaps I should have not used the word parameters (so that things would be less muddled).

To me independent and dependent are clear ways of writing it. But I've seen "parameter" being used in so many ways that I'm always confused.

The problem a novice faces with a "constant" is he assumes it is a "constant" so kind of counter-intuitive that the regression is trying to determine his "constant". i.e. If you ever have to manually do a least-squares regression the constants are variable and the variables are multiple constants.  ;D

Offline Corribus

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Re: Kinetics data
« Reply #20 on: August 27, 2013, 12:17:35 PM »
It's a constant in that it's not being varied as part of the experimental design.  You have the independent variable, which is the experimental variable; you have the dependent variable, which is the quantity you measure as a function of the independent variable; and you have a series of parameters, constants, etc., that scale the dependent variable.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

Offline Babcock_Hall

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Re: Kinetics data
« Reply #21 on: August 27, 2013, 12:43:07 PM »
IMO adjustable parameters are those things that we vary in order to minimize a particular function in regression.  In linear regression, the adjustable parameters are the slope and y-intercept.  I am not sure that everyone likes this terminology or thinks that it is best.

Offline Corribus

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Re: Kinetics data
« Reply #22 on: August 27, 2013, 12:45:58 PM »
I usually call them fit parameters, whether the fit is linear or not.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

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