"Martin Rowley" wrote in message
...

... it's probably worth saying as well, don't get too 'hung up' on the
absolute value! Obviously today is an interesting situation, but for
most purposes, your unit sounds as if it is giving a reasonable idea of
the 'ups and downs' in the pressure field, and it is these, particularly
the rate of change over 3, 6, 12 and 24hr that are important, rather
than the value itself.

Thank you for your help on this, and yes, I agree with your point on the
absolute value - I did not mind that it was +/- 1 when I began recording -
the nearest official station is far enough away for my reading to have as
good a chance of being correct as incorrect - and as you say, it is the
pattern in the data which matters most.

I was quite uncomfortable today with recording a 'record' reading
(regardless of if it was right or wrong) as on uncertified equipment it
would not be a 'record' anyway.

I shall repeat the comparisons which I made when I got the unit, but for the
longer period as you suggested - it will be interesting - and gives me more
statistics to analyse - every cloud .......

Gianna