(My) Hazy Numbers

After looking at yesterday’s data, I think I agree with NEA that you need at least a 3-hour average reading to make it reliable. It’s the minimum samples that you require to have a meaningful data. The 1-hour estimates simply fluctuate too much (or the model is too simple, perhaps it can be modelled better from the 3-hour reading). The ‘lag’ problem still persists, though, so I suppose there is still room for one more variable to indicate the ‘current trend’ of the data and have some predictive value to it.

Update: Apparently the problem lies in the piecewise linear relationship between PM10 concentration and PSI value, as highlighted in this excellent post.


PSI reading from 17/06/13 5am to 21/06/13 10am. Most of the PSI 3-hour readings are given by NEA while the rest (e.g., those between 1AM-5AM) and the 1-hour estimates are back-calculated from the 3-hour readings. Note the very large fluctuation in the 1-hour estimates.


4 thoughts on “(My) Hazy Numbers

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s