Just an observation - TICK and TIKI readings from different data vendors varies a lot.
So if you find a particular one from a specific data vendor that you can find some senses out of it then stay with that data feed.
Why difference among the data vendor?
It is because the TICK and TIKI are sampled statistics.
Some broadcast a subset of updates from the exchanges.
But some data vendors construct their own!
Thus the variation is huge in terms of update frequency from every second to every 30 secs.
Why difference when sampled at difference time?
Here is an example. A, B, C, D, and E are symbols.
Up means an up tick just happened and has a value of +1.
Down means a down tick just happened and has a value of -1.
So the TICK value is the sum of these up and down.
15:00:01
A up
B down
C up
D down
E down
the tick count here is -1
Now, 15:00:02
A up
B up
C up
D up
E down
the tick count here is +3
So, if your data vendor or simply the exchange sampled the market at 15:00:01, you get -1. If the sampling took place at 15:00:02, then you get +3.
At the very fast pace of # of transactions we have now, TICK can varies by as much as 100 to 200 from data vendor to data vendor.
Remember that due to the change into decimal system, data is no longer changed at 1/8 or 1/16 or 1/32. Thus many players are willing to play "unfair" and create "odd" ticks that is 0.01 above or below previous price.
That can never happen to NYSE data - because only best bid/ask got executed. But for NASDAQ, its TICKQ index is pretty much broken now.