1885.txt, Phil Jones vet ikke hvordan han legger til trendlinje

[Jostemikk]

En ufattelig e-post utveksling mellom Bob Ward og Phil Jones om statistikk. Det dreier seg om at noen har vært så slemme at de har sagt at det ikke har vært statistisk signifikant oppvarming de siste årene. Så viser det seg at "verdens ledende klimatolog" ikke er i stand til å lage en graf på Excel, langt mindre har han peiling på hvordan man får til en lineær trendlinje. Tror dere meg ikke? Ta en titt på denne, og husk at vi snakker om en som er gitt tilliten å vise verden den globale temperaturen:

Dear Phil,

I was wondering whether you have seen the article by David Whitehouse in the latest edition of 'New Statesman'? [3]http://www.newstatesman.com/200712190004

It would be great if somebody could respond to the article. I would be happy to do so if somebody can supply me with the ammunition. Any thoughts?

Best wishes,

Bob

From: Phil Jones
Sent: 20 December 2007 13:58
To: Bob Ward
Subject: Re: More nonsense on climate change

Bob,
Quickly re-reading this it sounds as though I'm getting at you. I'm not - just at the idiots who continue to spout this nonsense. It isn't an issue with climatologists. All understand. If I tried to publish this I would be told by my peers it was obvious and banal. I will try and hide it in a paper at some point. I could put it on the CRU web site. I'll see how I feel after the Christmas Pud.

I would have thought that this writer would have know better! I keep on seeing people saying this same stupid thing. I'm not adept enough (totally inept) with excel to do this now as no-one who knows how to is here.

What you have to do is to take the numbers in column C (the years) and then those in D (the anomalies for each year), plot them and then work out the linear trend. The slope is upwards. I had someone do this in early 2006, and the trend was upwards then. It will be now. Trend won't be statistically significant, but the trend is up.

This is a linear trend - least squares. This is how statisticians work out trends. They don't just look at the series. The simpler way is to just look at the data. The warmest year is 1998 with 0.526. All years since 2001 have been above 0.4. The only year before 2001 that was above this level was 1998. So 2cnd to 8th warmest years are 2001-2007

The reason 1998 was the warmest year was that it resulted from the largest El Nino event of the 20th century in 1997/8. We've not had anything resembling a major El Nino event since - they have all been minor.


Using regression, it is possible to take the El Nino event into account (with a regression based on the Southern Oscillation Index). This accounts for about 0.15 deg C of 1998's warmth. Without that 1998 would have been at about 0.38.

There is a lot of variability from year-to-year in global temperatures - even more in ones like CET. No-one should expect each year to be warmer than the previous. The 2000s will be warmer than the 1990s though. This is another way of pointing out what's wrong with their poor argument. The last comment about CET is wrong. 2007 will be among the top 10 warmest CET years - it will likely be 2cnd or 3rd.

Cheers

Phil

Dear Phil,

Thanks for responding so comprehensively. I have plotted the data before, and as you observe, the trend is up but the result isn't statistically significant, which I think makes it open to attack. I think the problem is that NOAA made the following statement in its report on the 2006 data:

"However, uncertainties in the global calculations due largely to gaps in data coverage make 2006 statistically indistinguishable from 2005 and several other recent warm years as shown by the error bars on the [1]global time series."


I'm not sure how to argue against this point - it appears to imply that there is no statistically significant trend in the global temperature record over the past few years.

Best wishes,

Bob[/i]

Hjelpe oss alle, for dette er horribelt. Er alt bare en drøm vi alle kan komme oss ut av hvis vi klyper oss hardt i armen, eller det snakk om en eller annen slags form for alternativ virkelighet?

[Amatør1]

Hvordan skal man tolke dette

This is a linear trend - least squares. This is how statisticians work out trends. They don't just look at the series.

Å, var det noen som trodde det? Er det et barn som snakker her, eller snakker han til et barn (Bob Ward)? Men Bob ser ut til å kunne litt av basisterminologien i det minste:

I have plotted the data before, and as you observe, the trend is up but the result isn't statistically significant, which I think makes it open to attack.

Jones framstår virkelig som over middels naiv. Det kan være hans beste kort i forsvaret av seg selv.


Oppdatering: Steve McIntyre observerer

Last year, Phil was ranked one of England's top 100 scientists. Just imagine the ranking that he could have achieved if he knew how to calculate a trend by himself.

         

Oppdatering 2 : Julegave til Jones Excel 2010 For Dummies

[Amatør1]

Trend won't be statistically significant, but the trend is up.

The reason 1998 was the warmest year was that it resulted from the largest El Nino event of the 20th century in 1997/8. We've not had anything resembling a major El Nino event since - they have all been minor.

Hvordan får Jones det til å være en stigende trend etter 1998 når han samtidig sier at 1998 var det varmeste året? Han er virkelig inkompetent?

[Jostemikk]

Her er den rette dataserien til Phil Jones, med trendlinje plottet for nøyaktig samme periode som nevnt i e-posten, nemlig fra 1998 til desember 2007:



Han har jo rett i at "den går oppover", men det er langt i fra noen statistisk signifikant stigning. Her er de tallene:

#File: hadcrut3gl.txt
#Time series (hadcrut3) from 1850 to 2011.75
#Selected data from 1998
#Selected data up to 2007.9
#Least squares trend line; slope = 0.00477727 per year

Alt dette var Bob Ward allerede fullstendig klar over da han startet denne e-post korrespondansen med Phil Jones. Han fisket rett og slett etter en måte å juge på i sitt tilsvar til David Whitehouse, slik at han kunne gi folk inntrykket av at Whitehouse var en bløffmaker.

Etter dette har det snart gått fire år. Disse fire årene har ikke gjort saken bedre for verken Bob Ward, Phil Jones eller resten av AGW-rørsla:



#File: hadcrut3gl.txt
#Time series (hadcrut3) from 1850 to 2011.75
#Selected data from 1998
#Least squares trend line; slope = 0.000292074 per year
1998   0.414847
2011.75   0.418863

Dette er 14 år uten temperaturstigning. I følge Santer og hans siste publikasjon, må det 17 år til før vi kan si noe sikkert. Dumt han ikke fortalte dette til James Hansen i 1988...

Skal vi ta en titt på 17 år og statistisk signifikant temperaturstigning, eller mangel på sådan?

Fra 1995:



#File: hadcrut3gl.txt
#Time series (hadcrut3) from 1850 to 2011.75
#Selected data from 1995
#Least squares trend line; slope = 0.00893841 per year
1995   0.313319
2011.75   0.463038

Kanskje Santer burde tatt en titt på temperaturstatistikken før han gikk ut og trodde han kjøpte seg noen friår?