"All the information can be found at the NIWA website."

No it can't.

But it's your call; show me where the code is; not general principles or results.

If by 'code', you mean a list of what adjustments were made and what data they were made, then you only have to search the site, cohenite.

For instance, here's a list of adjustments detailing what was done to what data.

http://www.niwa.co.nz/sites/default/files/import/attachments/7-Station_Temperature-Series.pdf

They also say that the raw data is available (free!), you only have to register to get a username and password.

I have not bothered, but I'm sure you will want to.

By the way, using this information the results can certainly be 'replicated', what they will not be is 'duplicated' (i.e. make an exact copy). You can either replicate their results, or apply your own adjustments the raw data (make sure they are justified for the time series you are adjusting!), and then you too can replicate the trend!

Amaze your friends and co-workers! No deposit, 15 months interest free!

Or amaze the experts at NIWA:

enquiries(at)niwa.co.nz

Should be good for a chuckle over afternoon tea : )

Bugsy and bonmot; NIWA has NOT provided code which can be placed in a model to produce an adjusted temperature trend from the raw data; they haven't even described an algorithm.

What has fooled you guys are general descriptors; those descriptors will refer to "overlaps" with neighbouring sites "composite" data and "correlation".

NIWA even admits to a subjective process when it says:

"Comparison stations were chosen subjectively,"

More specifically Appendix 1 & 2 of bonmot's link shows that there is no actual code to replicate the process. Appendix 1 of the Dunedin site references the "technical" procedure described at Appendix 2 of the Masterson site:

https://www.niwa.co.nz/sites/default/files/import/attachments/Masterton_CompositeTemperatureSeries_13Dec2010_FINAL.pdf

The first line establishes that there is NO meaningful code to proceed with:

"First, climatologies and anomalies are calculated for maximum temperatures at Waingawa in each calendar month from 1943 to 1972."

Well brainiacs, HOW are they calculated?

Do some homework, start here: enquiries(at)niwa.co.nz

Hey Mr 'climate statistics expert', why don't you just download the raw unadjusted "as measured" data from http://www.cliflo.niwa.co.nz and determine the temperature trend yourself? You can even apply your own adjustments, whatever you think is reasonable.

That would be a true replication, using the same raw data. If you come up with something anomalous or majorly in error compared to the NIWA results, please let everyone know, especially NIWA?

Maybe you could even get this one published...