Average temperature: Difference between revisions

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Average temperature (view source)

Revision as of 17:05, 30 May 2013

941 bytes added ,  30 May 2013
m
Clearer explanation of Cumulus processing and use of term 'mean' as on view screen
m (Explaining 'Today.ini' role)
m (Clearer explanation of Cumulus processing and use of term 'mean' as on view screen)
The average temperature for the day, as recorded in the [[dayfile.txt]], is calculated by Cumulus using samples of the datatemperature taken at 1-minute intervals (sometimes called the 'integration method'). (This offersassumes Cumulus is running continuously, if it has just been restarted, for some station types anCumulus alternativewill touse the simpletemperatures averagestored ofat the highestconsole andlogging lowestinterval temperaturesfor ofthe period since Cumulus previously ran). Each minute the day,new andmeasurement canis giveadded aonto the accumulator 'better'Total'' averageand increments by one the counter ''Samples'' in casesthe where[[today.ini]] log file. At rollover, the high''AvgTemp'' orfield lowin temperature[[yesterday.ini]] occurredholds forthe afinal relativelyintegrated shortmean period,calculated soby couldthe skewquotient of Total over Samples in the simpleold averagetoday.ini.
 
This offers an alternative to the simple mean of the highest and lowest temperatures of the day, and can give a 'better' average in cases where the high or low temperature occurred for a relatively short period, so could skew the simple average. To compare the two, select ''This period'' from the '''view''' menu and by default it will show both the integrated mean and simple mean temperatures for yesterday when you click '''Update display'''.
 
Note that statistically, a median temperature could be used, this would require holding all the individual measurements for a day, ranking them in order of magnitude and quoting the central value in that list (again this means extreme values have less skewing effect) - Cumulus does not retain the every minute individual values and cannot calculate median. If you wanted to compare daily median and daily mean, you would need to analyse the monthly log file with an external package.
 
 
The [[today.ini]] log file holds ''Total'' and ''Samples'' to enable the constant recalculation of the '''average temperature'''. In [[yesterday.ini]] the ''AvgTemp'' field holds the final average calculated by the quotient of Total over Samples in the old today.ini at rollover.
 
[[Category:Terminology]]
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