[Uncle Skeleton]

Originally Posted by smacintush 

Where is the evidence that people will get this? they certainly don't seem to, to understand it would require thinking and I don't think that people like to do that anymore. It's easier to react and people react more easily to those that mention the totalitarian aspects of the environmental movement as nuts and conspiracy wackos.

That's because the nuts and wackos are the only ones who have been willing to try arguing this point up until now. I haven't heard any moderate voices seriously argue that even though climate change is a real threat, there actually are more important considerations. You (and most true conservatives) can't expect anyone to come around to your side when you've been wasting your time on this strategy of arguing that the truth isn't true, and not spending any time to present your real contention.

I am desperate, the situation seems hopeless.

Your argument makes you appear that way... maybe you just think you are because you've been listening to your own arguments too long

[ShortcutToMoncton]

Haha did anyone read the interview? He didn't say "no GW since 1995."

Geez people.

greg

[olePigeon]

I mentioned that in another thread, apparently I missed this main thread on the subject. It doesn't say anything of the sort, but it's what spacefreak wants it to say. Why rob him of his dreams?

[Warren Pease]

There's nothing like some good honest journalism from decent folk who just want answers.

The Quote

However, Seymour's theories won qualified support from an unexpected source. Richard Dawkins, professor for the public understanding of science at Oxford University, who once suggested that astrologers be prosecuted under the trades descriptions act, said that although he had not read the book Seymour's ideas sounded interesting.

The reality

Originally Posted by Dawkins

"No. I most emphatically did NOT give my support to Percy Seymour. I was telephoned by a journalist called Jonathan Leake from the Sunday Times who asked me for a comment on Seymour's book. I said I hadn't read it, and therefore could not comment. Leake then read me part of the jacket blurb, which said something about magnetic fields before birth having an influence. I said something sarcastic like, "Well, that's very interesting, no doubt, but what the hell has it got to do with astrology?" The next thing I knew, the newspaper quoted me as 'supporting' Seymour by saying his work was 'interesting'. I am furious about this gross misrepresentation, and you may publish my disclaimer, if you wish."

Apparently, this guy, Leake, is good at this "journalism" thing.

[Uncle Skeleton]

Originally Posted by Warren Pease 

There's nothing like some good honest journalism from decent folk who just want answers.

The Quote


The reality


Apparently, this guy, Leake, is good at this "journalism" thing.

Well, that's very interesting, no doubt, but what the hell has it got to do with this thread?

[olePigeon]

Uncle Skeleton supports Jonathan Leake's "journalism!"

[stupendousman]

Originally Posted by ShortcutToMoncton 

Haha did anyone read the interview? He didn't say "no GW since 1995."

Geez people.

greg

Well, he did say that there was no " ‘statistically significant’ warming and I'm guessing that even that claimed insignificant amount can be questioned since a lot of the data involved can't be checked and we've got a lot of credible people are making claims that the very nature of data collection has been manipulated to try to pull warmer numbers.

What we do know is that the prediction years ago that by this time it would be hotter than it was then and cause all kinds of human calamity hasn't panned out and the "consensus" that there would be such disasters (requiring huge amounts of lifestyle change, cash investment and government intervention) was based on fraud.

So, I really wouldn't laugh too hard in defense of that idiot Jones.

[ShortcutToMoncton]

Originally Posted by stupendousman 

Well, he did say that there was no " ‘statistically significant’ warming and I'm guessing that even that claimed insignificant amount can be questioned since a lot of the data involved can't be checked and we've got a lot of credible people are making claims that the very nature of data collection has been manipulated to try to pull warmer numbers.

No, you missed the point: the trend is not statistically significant only because of the short time frame involved.

"Climate" is generally measured in 30-year norms; it's pretty much impossible to take any given 15-year period and say "oh, this is statistically significant one way or the other." However if our current temperature record continues on as it is (i.e. the hottest on temperature record) into the future, then it will become statistically significant. On that note, it's interesting that you've all seemed to ignore the part where he says "the trend is positive" during this time.

What we do know is that the prediction years ago that by this time it would be hotter than it was then and cause all kinds of human calamity hasn't panned out

AFAIK our current temperature records fall within IPCC predictions from surprisingly early on?

greg

[Big Mac]

I see desperation.

[Wiskedjak]

Originally Posted by Big Mac 

I see desperation.

Yep. The subject of this thread is a clear example of desperation by those opposed to the idea of human assisted climate change.

[Lint Police]

Originally Posted by Wiskedjak 

Yep. The subject of this thread is a clear example of desperation by those opposed to the idea of human assisted climate change.

The earth is not your mother. Stop acting like acting like she cries every time you exhale.

[stupendousman]

Originally Posted by ShortcutToMoncton 

Climate" is generally measured in 30-year norms; it's pretty much impossible to take any given 15-year period and say "oh, this is statistically significant one way or the other."

Why 30? We are talking about a planet that's pretty old. It would seem to me that any handful of years you cherry pick to measure could warrant panic when you don't look at it from a bigger perspective. That's why people like Jones wanted to negate the warmer climate that happened not all that long ago, though considerably more than 30 years.

Yes, I do smell desperation. That's what happens when "the jig is up." Lot's of money and reputations are on the line here.

[Uncle Skeleton]

Originally Posted by stupendousman 

Why 30?

Don't know much about statistics, do you?

Lot's of money and reputations are on the line here.

Like yours?

[stupendousman]

Originally Posted by Uncle Skeleton 

Don't know much about statistics, do you?

Some.

Why 30?

What makes 30 better than 15 over billions of years, statistically? If you take 4.5 billion of something and try to determine what falls within the norm, are you really saying that a sample difference of 15 makes a significant statistical difference?

Really?

Like yours?

I'm not the guy with the burden of proof on my shoulders, and I only lose if we have to invest my tax dollars into a fraudulent boondoggle.

[Uncle Skeleton]

Originally Posted by stupendousman 

Why 30?

What makes 30 better than 15 over billions of years, statistically? If you take 4.5 billion of something and try to determine what falls within the norm, are you really saying that a sample difference of 15 makes a significant statistical difference?

The whole purpose of statistics is to answer that question, objectively. This isn't a philosophical question, it's a math question. The answer is determined by the data set.

[Snow-i]

Originally Posted by Uncle Skeleton 

The whole purpose of statistics is to answer that question, objectively. This isn't a philosophical question, it's a math question. The answer is determined by the data set.

Lies, damned lies, and statistics.

[Wiskedjak]

Originally Posted by stupendousman 

I'm not the guy with the burden of proof on my shoulders, and I only lose if we have to invest my tax dollars into a fraudulent boondoggle.

Only, eh? Sounds like a pretty big lose to me.

[Wiskedjak]

Originally Posted by Lint Police 

The earth is not your mother. Stop acting like acting like she cries every time you exhale.

lol

[ironknee]

global warming or not... don't you want the environment cleaned up? just for living's sake?

for your kid's health?

or is it also a religious reason for not supporting the environment?

[Wiskedjak]

Originally Posted by ironknee 

or is it also a religious reason for not supporting the environment?

The Bible instructs Christians to "fill the earth and subdue it" and to "have dominion over the fish of the sea and over the birds of the air and over every living thing that moves upon the earth".

[stupendousman]

Originally Posted by ironknee 

global warming or not... don't you want the environment cleaned up? just for living's sake?

for your kid's health?

Sure. I'm just not entirely convinced that the fuel that plants need to survive and that human life produces is actually polluting the environment and doing the harm it's being accused of.

Chemicals and gases which are harmful to plant life and human's physical health, which isn't created naturally as a part of the normal life-cycle, I'm all for trying to reduce reasonably.

[stupendousman]

Originally Posted by Uncle Skeleton 

The whole purpose of statistics is to answer that question, objectively. This isn't a philosophical question, it's a math question. The answer is determined by the data set.

I wasn't asking a philosophical question. I was asking a math question.

Why, mathematically?

We know that the potential data set is about 4.5 billion in size. Mathematically, why would there be a significant statistical difference between a sample size of 15 as compared to 30 in a data set of 4.5 billion for determining a natural norm? Is a sample of 30 out of 4.5 billion even statistically relevant for determining this norm?

If there's a mathematical answer, feel free to give it.

[OreoCookie]

Originally Posted by stupendousman 

Why 30? We are talking about a planet that's pretty old. It would seem to me that any handful of years you cherry pick to measure could warrant panic when you don't look at it from a bigger perspective.

Originally Posted by stupendousman 

Why, mathematically?

Because different processes that are involved in the dynamics of the climate live on different scales so you won't see them if your average is too fine or too coarse.

Originally Posted by stupendousman 

We know that the potential data set is about 4.5 billion in size. Mathematically, why would there be a significant statistical difference between a sample size of 15 as compared to 30 in a data set of 4.5 billion for determining a natural norm? Is a sample of 30 out of 4.5 billion even statistically relevant for determining this norm?

If there's a mathematical answer, feel free to give it.

This has nothing to do with statistics, it's a fact of multiscale systems. If you look at the earth's rotational axis in terms of days or even a year, you won't see that the Earth precesses around its axis roughly once every 25,700~25,800 years. Your observational period is way too short.

On different scales different effects are important. On shorter scales, you don't have to take the movement of the continents into account while for longer ones (millions of years), you do.

This is different from statistics: to accurately estimate the period of precession of the Earth, you have to measure the periods of precession several times, i. e. you repeat a measurement. Your measurement wouldn't be statistically more significant if you were to measure the position of the axis daily (hypothetically) than in 10-year increments.

In short: the motivation to look at, say, 30-year increments doesn't come from statistics.

[Uncle Skeleton]

Originally Posted by stupendousman 

I wasn't asking a philosophical question. I was asking a math question.

Why, mathematically?

If there's a mathematical answer, feel free to give it.

The statistical significance is inversely proportional to the variance and proportional to the sample size. They have found through trial and error that a sample size of 15 is insufficient given the usual variance of this system (the earth), but 30 is sufficient, given the usual variance. That's why even though the trend is positive for a sample of 15, they are not surprised that the trend is insufficient for statistical significance.

We know that the potential data set is about 4.5 billion in size. Mathematically, why would there be a significant statistical difference between a sample size of 15 as compared to 30 in a data set of 4.5 billion for determining a natural norm? Is a sample of 30 out of 4.5 billion even statistically relevant for determining this norm?

It doesn't matter (to your question) how large a data set can be, because you are asking how small can we make it. Your question is "what is the minimum data set for statistical significance (and is it somewhere between 15 and 30)." Your quote tells us it's less than 4.5 billion. Duh.

[Uncle Skeleton]

Originally Posted by OreoCookie 

This has nothing to do with statistics, it's a fact of multiscale systems. If you look at the earth's rotational axis in terms of days or even a year, you won't see that the Earth precesses around its axis roughly once every 25,700~25,800 years. Your observational period is way too short.

On different scales different effects are important. On shorter scales, you don't have to take the movement of the continents into account while for longer ones (millions of years), you do.

This is different from statistics: to accurately estimate the period of precession of the Earth, you have to measure the periods of precession several times, i. e. you repeat a measurement. Your measurement wouldn't be statistically more significant if you were to measure the position of the axis daily (hypothetically) than in 10-year increments.

In short: the motivation to look at, say, 30-year increments doesn't come from statistics.

Are you saying that climate change is due to the precession of the earth? If not I don't see how your answer is relevant to the question.

[OreoCookie]

Originally Posted by Uncle Skeleton 

Are you saying that climate change is due to the precession of the earth? If not I don't see how your answer is relevant to the question.

No, the precession of the earth was just an example of a system that lives on different scales (1 day and ~26,000 years). stupendousman wanted to know how to justify choosing 30 years as a period over which to average instead of 15 years (or even shorter times) mathematically.

What I meant to say was that to be able to observe some effects, you need to choose certain time scales. The time scales may be very different for different effects. To observe the rotation of the earth, the time scale of, say, 1 hour is good. To observe the precession of the Earth's axis of rotation, the time scale of 1 hour is bad, because you cannot observe the precession on this time scale. Conversely, you do not see the rotation of the Earth on the time scale hundreds/thousands of years while you can see the precession. But this is just an example for a simple two-scale system that didn't necessarily have anything to do with climate sciences. It was just used for illustration of my explanation. The climate is obviously more complex than that and has many more scales.

The second point is that this choice of time scale has nothing to do with statistics. stupendousman insinuates that scientists choose this time scale because it `shows what they want' (i. e. manipulation) and wonders if you don't get better statistics with shorter averaging intervals. This is not the case.

[besson3c]

Originally Posted by stupendousman 

Sure. I'm just not entirely convinced that the fuel that plants need to survive and that human life produces is actually polluting the environment and doing the harm it's being accused of.

Chemicals and gases which are harmful to plant life and human's physical health, which isn't created naturally as a part of the normal life-cycle, I'm all for trying to reduce reasonably.

What would it take to convince you?

[ort888]

Originally Posted by besson3c 

What would it take to convince you?

When it becomes a Republican talking point.

[Uncle Skeleton]

Originally Posted by OreoCookie 

The second point is that this choice of time scale has nothing to do with statistics. stupendousman insinuates that scientists choose this time scale because it `shows what they want' (i. e. manipulation) and wonders if you don't get better statistics with shorter averaging intervals. This is not the case.

I don't think the number of years is about time, it's about sample size. You can really only use one measurement per year, to make them comparable, so the number of years dictates the number of measurements. That's what it has to do with statistics.

[OreoCookie]

Originally Posted by Uncle Skeleton 

I don't think the number of years is about time, it's about sample size. You can really only use one measurement per year, to make them comparable, so the number of years dictates the number of measurements. That's what it has to do with statistics.

But it doesn't mean you're improving your statistics, on the contrary. It's like measuring the growth of grass by measuring the length of the blades every second with a ruler: it won't give you better statistics, because for most of the time, you don't see any change (the ruler will tell you that within the uncertainties of, say, 0.5 mm, the length hasn't changed since last second. That's one example where shortening the period won't give you any improvement.

With weather, the situation is different and even worse: there are short-term fluctuations which may even dominate the signal. This means, there are a lot more fluctuations in your initial data which in turn destroys your statistics as the standard deviations are larger. You have to take averages over certain characteristic time scales to see certain trends and effects that live on that time scale.

[Uncle Skeleton]

Originally Posted by OreoCookie 

But it doesn't mean you're improving your statistics, on the contrary. It's like measuring the growth of grass by measuring the length of the blades every second with a ruler: it won't give you better statistics, because for most of the time, you don't see any change (the ruler will tell you that within the uncertainties of, say, 0.5 mm, the length hasn't changed since last second. That's one example where shortening the period won't give you any improvement.

No, false analogy, because we can measure temperature with far more (relative) accuracy than a ruler against a blade of grass, and our measurements are stymied by too much change, not too little change (I know you know this because you said it yourself). If the grass jumped taller and shorter 100 times a second and we were measuring it with a microscope, that would be a fair analogy.

With weather, the situation is different and even worse: there are short-term fluctuations which may even dominate the signal. This means, there are a lot more fluctuations in your initial data which in turn destroys your statistics as the standard deviations are larger.

Noise doesn't "destroy" statistics, noise is the reason for statistics. If it weren't for the noise, we could just measure it directly like your blade of grass example; there would be no analysis required. The noise is exactly why statistics are needed.

You have to take averages over certain characteristic time scales to see certain trends and effects that live on that time scale.

AGW predicts the temperature to rise steadily. Any timescale-specific trends in climate are natural ones, which only serve to mask the artificial trend. So I don't know why you're bringing them up.

[ironknee]

Originally Posted by stupendousman 

Sure. I'm just not entirely convinced that the fuel that plants need to survive and that human life produces is actually polluting the environment and doing the harm it's being accused of.

Chemicals and gases which are harmful to plant life and human's physical health, which isn't created naturally as a part of the normal life-cycle, I'm all for trying to reduce reasonably.

can't help but bring up the movie Apollo 13.

too much of the natural gas carbon dioxide is not good for life

[OreoCookie]

Originally Posted by Uncle Skeleton 

Noise doesn't "destroy" statistics, noise is the reason for statistics. If it weren't for the noise, we could just measure it directly like your blade of grass example; there would be no analysis required. The noise is exactly why statistics are needed.

To improve the signal-to-noise ratio by averaging is well-known in the scientific world. For an animated example, have a look here.

If you are looking at a progression with variations on a longer time scale superimposed by short scale noise, averaging clears up the signal. The averaging window mustn't be too large, it should be strictly smaller than the typical variation length of long-time variations you're interested in. The longer the window gets, the more the noise is averaged out. Hence, if you choose the averaging window properly, you improve the signal-to-noise ratio. That's my main point.

It's not an argument about whether or not statistics is necessary, but how to process your data so as to get the best signal. For that, you need to know what you're looking for.

[Orion27]

Of course all measurements and statistics are meaningless without a reliable and consistent data source. I guess the "scientists" at NOAA and NASA were trying to eliminate some of the static by reducing the number of data points from 6500 to 1500. EDITORIAL: More errors in temperature data - Washington Times

[Doofy]

Originally Posted by ironknee 

can't help but bring up the movie Apollo 13.

too much of the natural gas carbon dioxide is not good for life

And yet instead of taxing Tom Hanks and Kevin Bacon to within an inch of their lives, Ed Harris decided to have them make a CO2 scrubber out of bits of old crap.

[ironknee]

Originally Posted by Doofy 

And yet instead of taxing Tom Hanks and Kevin Bacon to within an inch of their lives, Ed Harris decided to have them make a CO2 scrubber out of bits of old crap.

doofy

that CO2 scrubber in this metaphor would be clean energy technology

and are you being taxed more now?

[smacintush]

Originally Posted by ironknee 

can't help but bring up the movie Apollo 13.

too much of the natural gas carbon dioxide is not good for life

That's one of the dumbest things I've seen you post.

Men trapped in an air tight container with no source of oxygen is somehow analogous to the AGW situation?

Not to mention the fallacy of your statement. There has been far more CO2 in the world before we were here and it wasn't dangerous to life. Life flourished.

[Uncle Skeleton]

Originally Posted by smacintush 

There has been far more CO2 in the world before we were here and it wasn't dangerous to life. Life flourished.

The fear isn't that life will stop, the fear is that human life will stop. It's a strictly selfish concern.

[Wiskedjak]

Originally Posted by smacintush 

There has been far more CO2 in the world before we were here and it wasn't dangerous to life. Life flourished.

The concern isn't that the environment is changing to conditions that were never present on this planet; we know that the world has been FAR colder and FAR hotter than we'll likely see any time soon. The concern is that humans might be causing a *rate* of change that is faster than life on this planet can easily evolve to accommodate.

[ebuddy]

Originally Posted by Uncle Skeleton 

The fear isn't that life will stop, the fear is that human life will stop. It's a strictly selfish concern.

Is there something about human life that would make it unique to non-human life that it wouldn't likewise flourish?

[ebuddy]

Originally Posted by Wiskedjak 

The concern isn't that the environment is changing to conditions that were never present on this planet; we know that the world has been FAR colder and FAR hotter than we'll likely see any time soon. The concern is that humans might be causing a *rate* of change that is faster than life on this planet can easily evolve to accommodate.

There's also a concern that humans might be causing much less a *rate* than is popularly assumed and the suggestions of what we'd have to adapt to have often been mistaken.

[ghporter]

Originally Posted by ebuddy 

Is there something about human life that would make it unique to non-human life that it wouldn't likewise flourish?

I think the point is that if human life stops, we won't be around to worry about it. Further, the very large environmental system of the Earth has a pretty good, though long time-scale ability to clean up that which is done by Man, whether it's dumping gunk in the water, in the air, or on the ground.

Not much of what we've done "for the betterment of Man" over the millennia has been particularly "kind and gentle" to the planet. It's just in the last couple of centuries that we've been able to do so much not-good stuff, and only in the last century that our not-good stuff has been so very not-good.

Whether or not Man has made long-term changes to the environment is one particularly thorny question. We have concrete evidence that NOT doing some of what we have done to the environment is beneficial; note that until the 1960s there were long trends of decreasing health and longevity in and around industrial areas, mostly attributable to bad stuff in the air and water, and that these trends reversed when environmental regulation of those identified pollutants was implemented and enforced.

Environmental awareness and good stewardship are Good Things, whether or not we are individually responsible for polar bears drowning.

[ebuddy]

Originally Posted by ghporter 

Environmental awareness and good stewardship are Good Things, whether or not we are individually responsible for polar bears drowning.

These are absolutely good things, but you'd also agree that good intentions do not always equate to positive outcomes. Environmental awareness and good stewardship are not exclusively the concerns of government entities. In fact, I'd say that most of us are as good if not better stewards of our environment than those who seek to adjust our behaviors.

[Wiskedjak]

Originally Posted by ebuddy 

There's also a concern that humans might be causing much less a *rate* than is popularly assumed and the suggestions of what we'd have to adapt to have often been mistaken.

Absolutely. I assumed that smacintush was already familiar with that concern. But, it was apparent that he didn't seem to accurately understand why some people are concerned about the possibility of human assisted climate change and I was merely seeking to help him form more effective arguments.

FWIW, I'm not convinced that we *are* affecting our planet's climate. But, I do think the risks of severe climate change, human assisted or not, are serious enough to warrant some consideration (much like some felt the risk of WMD in the hands of Saddam Hussein warranted action against Iraq despite a lack of evidence).

[Wiskedjak]

Originally Posted by ebuddy 

Is there something about human life that would make it unique to non-human life that it wouldn't likewise flourish?

I think it's safe to say that some forms of life on our planet are better suited to some extreme climate conditions than others. Polar bears are much better suited to life in extreme cold and camels are better suited to life in extreme heat than we are. We are capable of using technology to assist us in living in extreme environments, but personally, I'd rather not since the cost of doing so will likely be quite high.

[ghporter]

Originally Posted by ebuddy 

These are absolutely good things, but you'd also agree that good intentions do not always equate to positive outcomes. Environmental awareness and good stewardship are not exclusively the concerns of government entities. In fact, I'd say that most of us are as good if not better stewards of our environment than those who seek to adjust our behaviors.

I would disagree with you on the "most of us" thing. "Most of us" are uneducated, ill-informed and often negligent about what they do. My hospital has signs all over that say we're a tobacco-free campus, but my fellow health care providers apparently smoke until they get to the door of the building, leaving a nasty mess of cigarette butts just outside... "Most of us" leave shopping carts in the handicapped parking spaces 15 feet from the shopping cart space because they're too busy with what they're doing to be bothered to put the cart away. "Most of us" sit in lines at fast food drive throughs with the engine running because they don't think about what they're doing.

"A lot of us" are aware and work at being good stewards of the areas around us. But we are in the minority. When you start looking at businesses, you find that stress on a bottom line makes even well intentioned business people cut corners wherever they can, and the environment is one spot they target frequently simply because they don't think about stewardship. In this case, I believe that simple rules for everyone are indicated, and those rules are indeed the territory of government regulation. I do not suggest that the EPA is going the way I would with regulation, but some regulation should be in place to ensure that good stewards are not handicapped in business by their good stewardship.

[ironknee]

Originally Posted by smacintush 

That's one of the dumbest things I've seen you post.

Men trapped in an air tight container with no source of oxygen is somehow analogous to the AGW situation?

Not to mention the fallacy of your statement. There has been far more CO2 in the world before we were here and it wasn't dangerous to life. Life flourished.

hello sunshine!

it's all about balance... too much of one thing is not healthy

[Uncle Skeleton]

Originally Posted by ebuddy 

Is there something about human life that would make it unique to non-human life that it wouldn't likewise flourish?

What makes us unique is that we're currently on top. If you change anything world-wide, we have nowhere to go but down.

[stupendousman]

Originally Posted by Uncle Skeleton 

The statistical significance is inversely proportional to the variance and proportional to the sample size. They have found through trial and error that a sample size of 15 is insufficient given the usual variance of this system (the earth), but 30 is sufficient, given the usual variance. That's why even though the trend is positive for a sample of 15, they are not surprised that the trend is insufficient for statistical significance.


It doesn't matter (to your question) how large a data set can be, because you are asking how small can we make it. Your question is "what is the minimum data set for statistical significance (and is it somewhere between 15 and 30)." Your quote tells us it's less than 4.5 billion. Duh.

AND

Originally Posted by OreoCookie 

No, the precession of the earth was just an example of a system that lives on different scales (1 day and ~26,000 years). stupendousman wanted to know how to justify choosing 30 years as a period over which to average instead of 15 years (or even shorter times) mathematically.

Would it be too much to ask one of you really intelligent guys to plug the numbers into all those complicated equations, starting with the 4.5 billion, to show me where the number 30 comes up?

I understand that the larger the sample, the greater the relevance. That wasn't being questioned. I'm asking to see exactly how 30 years came to be used and how when looking at something 4.5 billion years old, a non-random sample of 30 years can be significant in finding the norm.

Thanks.

[Uncle Skeleton]

First, yes it is too much. I'm not going to look at the raw data for you

Secondly, you have to answer this misunderstanding for us. I think you mean "how long does it take to detect a change" and Oreo thinks you mean "if one period shows a change and a different (shorter) period shows no change, why can't I just look at the period that shows what I want to see." Which question are you really asking?

Lastly, the age of the earth isn't relevant here. Consider this question, "are you gaining weight or losing weight at this point in your life?" To answer this, you would have to take measurements over time and average them. The samples wouldn't trend in an exactly straight line (they rise and fall with your daily, um, business), and how variable they are (signal to noise ratio) dictates how long you need to average before you can have confidence in your answer. A period of 12 hours is obviously too short to get an accurate answer, and a period of 3 days is probably too short as well, but a period of 7 days might be long enough. How do we know when we have measured long enough? We don't, until we try it and see if the signal/noise ratio is high enough at each of those periods. Knowing your age first doesn't enter the equation. The question isn't about whether you weigh more now than the day you were born, and it's not whether you weigh more now than at any previous point in your life. Your age is relevant to those questions, but not to the one we asked.