What does it mean for a trend to be 'statistically significant'? - what does perrier do to hookah
Penny asked, with the initials MF: "How many years of cooling would be statistically significant?" But it seems, was not in the answer as the best answer is "not prepared to respond even remotely interested to question.
Thus, for the benefit of those who are really interested in the answer, because so little seems to understand that the refusal of a "trend was statistically significant, what?
Sunday, January 31, 2010
What Does Perrier Do To Hookah What Does It Mean For A Trend To Be 'statistically Significant'?
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This means your response is probably due to noise on a certain confidence level (CL) is based. Very few people in the blogosphere will always be the CL, but usually occurs in any work of peer review. In fact, a document may be rejected without yeast, because the term "statistical significance is meaningless without an LC. What is the most commonly used in science and technology is 95% of CL, which is about 2 standard deviations.
There is always a possibility that your response to noise, but CL gives the probability that is not their answer is true and what is just noise.
This means your response is probably due to noise on a certain confidence level (CL) is based. Very few people in the blogosphere will always be the CL, but usually occurs in any work of peer review. In fact, a document may be rejected without yeast, because the term "statistical significance is meaningless without an LC. What is the most commonly used in science and technology is 95% of CL, which is about 2 standard deviations.
There is always a possibility that your response to noise, but CL gives the probability that is not their answer is true and what is just noise.
In short, this means that the trend is unlikely that the result of pure noise * and that a kind of property is based reflects underlying data. In general, a result that is statistically significant is a result that should not occur by chance.
If the result is significant, depends on the amount of data you have, how big is the signal, and how the data are noisy. If the data are very noisy, and the signal is very weak, it will be impossible to obtain meaningful results within a short timescale.
Climate data are very noisy, so try to trends in a very short time scales to be found, is like trying to take a mountain morning in dense fog. The deniers are shown happy and seeing all the beautiful colors whinny, not once, however, and actually applied in whorls and eddies in the fog.
A trend is significant if the null hypothesis is rejected. On the basis of the evidence and the methods used can vary widely null hypothesis. There is also a _a priori_ quality of service, "said Beren. The 95% is the most common, but I see 90% of the CL, most often in the literature, especially in the biological relationship.
I do not agree with the assessment of previous P Keith, who says that ror ^ 2 is the total value metric is important because both R and R ^ 2 can be any number of parameters in the model and the sample size.
A model with the parameters of 1000 will have a high in the sky r ^ 2, regardless of the actual correlation.
In terms of global temperatures, this is a debate (too long and too good for a quick summary to say much, but I give you one anyway) on the same topic. Written by a statistician.
http://tamino.wordpress.com/2008/01/31/y ...
OK, a very rough set. Two or more years of warming temperature trend line and 30 years a steady trend line for 2 or more standard deviations are not warm. Figure 4 shows the pages visually, which is much easier to understand than words.
We are not even close to unusually cold weather since 1999 and 2000, followed an unusually warm year 1998. And they were not so close.
The second graph on the site, which completely destroyed the "we are not warming" argument. After 2000 every year run to 30 will be very close to the line of warming
EDIT - The following statement glosses over a lot. an increase of less than one degree over a hundred years "statistically significant"? "Absolutely. Andit is "alarming".
On the one hand, unprecedented in the last 2000 years. In the magnitude (minor point) and, more importantly, the speed (of something that it is difficult to master, does). DATA.
http://www.globalwarmingart.com/images/c ...
One degree Celsius is already causing a significant impact and important. Two of these effects significantly expensive to treat. Three would be an economic disaster.
In relation to this part of the issue:
"best response" chosen in a distance in order to answer the question. "
Do not take it too seriously. I think sometimes he asks receives few responses just make too much fuss.
Take a coin and get his head. One could say that * always * up, on the basis of a sample is not statistically significant. Tell me, flip-8-fold. There is a probability of 1 / 256, 8 times that all the targets. Flipping 8 times greater than 1 is statistically significant. Even if the weather grew colder for 8 years in a row, would climate scientists are very interested.
Take a coin and get his head. One could say that * always * up, on the basis of a sample is not statistically significant. Tell me, flip-8-fold. There is a probability of 1 / 256, 8 times that all the targets. Flipping 8 times greater than 1 is statistically significant. Even if the weather grew colder for 8 years in a row, would climate scientists are very interested.
This means that the correlation coefficient r> .7, or R ²> .5. In general, the climate must be based on at least 30 years of data, otherwise the long run is too short (ie, the time) not the weather.
For info to be 360 months 9-79 to 9-09, the correlation coefficient r five sets of data on global temperatures:
HAD 76
UAH, 78
GISS, 87
NCDC, 88
RSS feeds, 95
It is interesting that the record had at least the confidence of the deniers, shows slight warming - although the five types of data is vital.
30 + years of cooling from the years 1940 to 1970 is not statistically significant.
25 years of warming since the mid-1970s until the late 1990s is statistically significant.
Unchanged from 10 years ago, despite the CO2 still not statistically significant.
Different rules - almost any amount or duration of heating is important, but any amount or duration of cooling is not required.
This means that the person reads, the data show a clear trend. Statistics for the people creating the report to define what they mean. In some cases, not the maximum temperature in the last 11 years. For others, it is assumed that in the last decade was the warmest.
\\ \\ \\ \\ \\ \\ \\ \\ U0026lt \\ \\ \\ \\ \\ \\ \\ \\ u0026lt; Oh, it's just beautiful. Let me see. . . an increase of less than one degree over a hundred years "statistically significant"? I do not think>>
Version of a penny "math"!
A few alarmists also understand what it is not statistically significant, because we mean no statistically significant warming since 1995.
http://wattsupwiththat.com/2008/03/11/a- ...
A few alarmists also understand what it is not statistically significant, because we mean no statistically significant warming since 1995.
http://wattsupwiththat.com/2008/03/11/a- ...
This means that you must stay by so-called standard deviation. 1 standard deviation over 66% at a greater distance from the possibility of a chance device is by him alone is less and less the farther you go.
Oh, it's just beautiful. Let me see. . . an increase of less than one degree over a hundred years "statistically significant"?
I think not.
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