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Meat Popsicle

11,709 posts

I have 2 data points I want to use to form a ratio. Each data point has some uncertainty associated with it. What's the best way to express the uncertainty associated with the ratio?

For example let's say data point one is: 48.513, 50.058, 29.513

and data point 2 is 259.519, 296.952, 317.482

I'll calculate the mean and std dev for each point and get a ratio, but I'm not sure how to get an uncertainty number for the error associated with the ratio. That and our stats guy is gone for the weekend.

Anyhoo, I'm google-ing away but feeling tired, just thought I'd see if I could get you people to do my homework for me.

For example let's say data point one is: 48.513, 50.058, 29.513

and data point 2 is 259.519, 296.952, 317.482

I'll calculate the mean and std dev for each point and get a ratio, but I'm not sure how to get an uncertainty number for the error associated with the ratio. That and our stats guy is gone for the weekend.

Anyhoo, I'm google-ing away but feeling tired, just thought I'd see if I could get you people to do my homework for me.

Soulless Internet Tiger

34,681 posts

23

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Deceased

21,717 posts

Uglysasquatch wrote:

(23-2)(2)

R.I.P. Jessica M. 5/3/2010

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gbaji wrote:

You guys keep tossing facts out there like they mean something.

Meat Popsicle

11,709 posts

BrownDuck wrote:

Uglysasquatch wrote:

(23-2)(2)

Needs more numbers, and maybe some funky math symbols, plus pi. All good equations have pi in them somewhere.

Sage

5,684 posts

Quote:

Anyone here able to answer a stats question?

Almalieque wrote:

I admit that I was wrong

God bless Lili St. Cyr

43,650 posts

42

George Carlin wrote:

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Meat Popsicle

11,709 posts

Bardalicious wrote:

Quote:

Anyone here able to answer a stats question?

That's fine, at least we have some pie now. Would you like some?

9,955 posts

Bardalicious wrote:

Quote:

Anyone here able to answer a stats question?

01001001 00100000 01001100 01001001 01001011 01000101 00100000 01000011 01000001 01001011 01000101

You'll always be stupid, you'll just be stupid with more information in your brain

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You'll always be stupid, you'll just be stupid with more information in your brain

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Meat Popsicle

11,709 posts

Sir Xsarus wrote:

Bardalicious wrote:

Quote:

Anyone here able to answer a stats question?

You're holding out on me aren't you... I knew it!

Encyclopedia

31,550 posts

someproteinguy wrote:

I have 2 data points I want to use to form a ratio. Each data point has some uncertainty associated with it. What's the best way to express the uncertainty associated with the ratio?

For example let's say data point one is: 48.513, 50.058, 29.513

and data point 2 is 259.519, 296.952, 317.482

I'll calculate the mean and std dev for each point and get a ratio, but I'm not sure how to get an uncertainty number for the error associated with the ratio. That and our stats guy is gone for the weekend.

For example let's say data point one is: 48.513, 50.058, 29.513

and data point 2 is 259.519, 296.952, 317.482

I'll calculate the mean and std dev for each point and get a ratio, but I'm not sure how to get an uncertainty number for the error associated with the ratio. That and our stats guy is gone for the weekend.

Um... Calculate the highest and lowest possible ratios and go from there? So lowest of one set to highest of the other, then the other way around. That gives you a single range of ratios. This assumes that the results aren't linked together directly (so one set is the variable output of one thing, the other the output of something else). If the sets are linked (each pair is the result of a interdependent test of some kind), then you'd want to treat them as three separate ratios and then go from there.

How you analyze it has to take into account how the data was generated. Otherwise, it's just garbage you used math(tm) on.

King Nobby wrote:

More words please

6,176 posts

lolgaxe wrote:

42

Sandinmyeye | **** | Dihydrogen Monoxide (it kills)

Meat Popsicle

11,709 posts

gbaji wrote:

someproteinguy wrote:

I have 2 data points I want to use to form a ratio. Each data point has some uncertainty associated with it. What's the best way to express the uncertainty associated with the ratio?

For example let's say data point one is: 48.513, 50.058, 29.513

and data point 2 is 259.519, 296.952, 317.482

I'll calculate the mean and std dev for each point and get a ratio, but I'm not sure how to get an uncertainty number for the error associated with the ratio. That and our stats guy is gone for the weekend.

For example let's say data point one is: 48.513, 50.058, 29.513

and data point 2 is 259.519, 296.952, 317.482

I'll calculate the mean and std dev for each point and get a ratio, but I'm not sure how to get an uncertainty number for the error associated with the ratio. That and our stats guy is gone for the weekend.

Um... Calculate the highest and lowest possible ratios and go from there? So lowest of one set to highest of the other, then the other way around. That gives you a single range of ratios. This assumes that the results aren't linked together directly (so one set is the variable output of one thing, the other the output of something else). If the sets are linked (each pair is the result of a interdependent test of some kind), then you'd want to treat them as three separate ratios and then go from there.

How you analyze it has to take into account how the data was generated. Otherwise, it's just garbage you used math(tm) on.

You're looking at 6 independent measurements. In 3 of them the protein is at one concentration and in 3 it is at another level. The sampling technique is analogous to estimating the number of, say, red balls in the bin by blindly reaching in and grabbing a few. Those numbers above being the number of 'red balls' you grabbed (the decimal places come from normalization based on the variable number of successful sampling attempts).

Along the lines you were thinking though, I was considering making 6 ratios out of the points by taking the three points and comparing them to each of the other three, and using those values to address the question. The problem is that ratios don't necessarily behave the same way when you do something like average them. So that's where I got stuck.

Looks like I may be grabbing my old stats book from college and having some fun reading over it this weekend...

Rate-ups for the brainstorming helps.

Drunken English Bastard

15,263 posts

Did you take the root mean square deviation at all?

That's what we always have to do for our experiential data to find the probable uncertainty value for our results. I'm just a student though, I don't know if you'd do it different professionally.

That's what we always have to do for our experiential data to find the probable uncertainty value for our results. I'm just a student though, I don't know if you'd do it different professionally.

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Mashed potatoes.

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Meat Popsicle

11,709 posts

Nilatai wrote:

Did you take the root mean square deviation at all?

That's what we always have to do for our experiential data to find the probable uncertainty value for our results. I'm just a student though, I don't know if you'd do it different professionally.

That's what we always have to do for our experiential data to find the probable uncertainty value for our results. I'm just a student though, I don't know if you'd do it different professionally.

No it's the right idea, for sure. I'm thinking what I need to do is calculate that for each of the two points and use something like this to combine the uncertainty from the two data points into a single value.

As an aside, I'd wager most students know more about these things than most "professionals"

Drunken English Bastard

15,263 posts

someproteinguy wrote:

Nilatai wrote:

Did you take the root mean square deviation at all?

That's what we always have to do for our experiential data to find the probable uncertainty value for our results. I'm just a student though, I don't know if you'd do it different professionally.

That's what we always have to do for our experiential data to find the probable uncertainty value for our results. I'm just a student though, I don't know if you'd do it different professionally.

No it's the right idea, for sure. I'm thinking what I need to do is calculate that for each of the two points and use something like this to combine the uncertainty from the two data points into a single value.

As an aside, I'd wager most students know more about these things than most "professionals"

That's the badger.

You're probably right on the students knowing more, though. Especially if you're doing labs week in week out. Tends to stick in the mind a bit. As you said, you do the experiment and you have a guy who specifically does the stats portion. It looks like you're on the right track, though!

My Movember page

Solrain wrote:

WARs can use semi-colons however we want. I once killed a guy with a semi-colon.

LordFaramir wrote:

ODESNT MATTER CAUSE I HAVE ALCHOLOL IN MY VEINGS BETCH ;3

Drunken English Bastard

15,263 posts

someproteinguy wrote:

I have 2 data points I want to use to form a ratio. Each data point has some uncertainty associated with it. What's the best way to express the uncertainty associated with the ratio?

For example let's say data point one is: 48.513, 50.058, 29.513

and data point 2 is 259.519, 296.952, 317.482

I'll calculate the mean and std dev for each point and get a ratio, but I'm not sure how to get an uncertainty number for the error associated with the ratio. That and our stats guy is gone for the weekend.

Anyhoo, I'm google-ing away but feeling tired, just thought I'd see if I could get you people to do my homework for me.

For example let's say data point one is: 48.513, 50.058, 29.513

and data point 2 is 259.519, 296.952, 317.482

I'll calculate the mean and std dev for each point and get a ratio, but I'm not sure how to get an uncertainty number for the error associated with the ratio. That and our stats guy is gone for the weekend.

Anyhoo, I'm google-ing away but feeling tired, just thought I'd see if I could get you people to do my homework for me.

So according to my girlfriend's SPSS Psychologist stat calculating thingy, the first data point should have a standard error of 6.605, the second should be 16.967.

Is that what sort of thing you're looking for?

My Movember page

Solrain wrote:

WARs can use semi-colons however we want. I once killed a guy with a semi-colon.

LordFaramir wrote:

ODESNT MATTER CAUSE I HAVE ALCHOLOL IN MY VEINGS BETCH ;3

Meat Popsicle

11,709 posts

Nilatai wrote:

So according to my girlfriend's SPSS Psychologist stat calculating thingy, the first data point should have a standard error of 6.605, the second should be 16.967.

Is that what sort of thing you're looking for?

That's the part I have done. Now let's say I form want to express the difference between the two data points as a ratio (i.e. 5.2:1). How does the uncertainty from the two measurements factor into the uncertainty of the resulting ratio?

Ghost in the Machine

36,048 posts

I have no idea what's going on, but it looks interesting.

6,176 posts

Something about how it all equals 42, but they are taking the long way to get there.

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Drunken English Bastard

15,263 posts

someproteinguy wrote:

Nilatai wrote:

So according to my girlfriend's SPSS Psychologist stat calculating thingy, the first data point should have a standard error of 6.605, the second should be 16.967.

Is that what sort of thing you're looking for?

That's the part I have done. Now let's say I form want to express the difference between the two data points as a ratio (i.e. 5.2:1). How does the uncertainty from the two measurements factor into the uncertainty of the resulting ratio?

I have absolutely no idea.

I'll ask my girlfriend later. She's better at stats, but I kick her **** at Algebra...

Sorry, SPG!

Solrain wrote:

WARs can use semi-colons however we want. I once killed a guy with a semi-colon.

LordFaramir wrote:

ODESNT MATTER CAUSE I HAVE ALCHOLOL IN MY VEINGS BETCH ;3

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