What does "Filtered Data" actually mean?

This is a commonly mis-understood topic.

All data received from the exchange is unfiltered....it is the "Refresh Rate" that is the difference.

Data feeds, use different refresh rates <refresh the last price shown on the trading platform>

This varies across all data-feeds...so we are unable to confirm any set standards for the "refresh rate" shown by each data feed (but we did recently ask all the data feeds and here are the official responses below).

Here are the "Refresh Rate" responses from Rithmic, CQG, TT, CTS:

Rithmic > "For users who do not connect to Rithmic aggregated feed, Rithmic streams the data so there is no refresh rate.  For users connecting to Rithmic aggregated feed the aggregation rate is about 100 milliseconds.  R | Trader and R | Trader Pro permit users, who are not connected to an aggregated feed, to set their own refresh rate.

CQG > "We do not conflate data by default. A software vendor may (or may not) decide if they want a data compression using API functionality." > Which means, it is up to the trading platform to set the Refresh Rate - per the trading platforms desired optimized settings.  From previous discussions with some of the trading platforms connected to CQG <125 milliseconds> is common.

TT > It's 100ms on TTW & TTD (TT Web & TT Desktop). All Algos (ADL) & Synthetic order types are running/triggered through un-throttled market data.  Also 100ms on TT FIX connections over the Internet.  We can provide un-throttled data via FIX, but only on a direct connect and with TT Reserve (dedicated bare metal server $2k/month).

CTS > we have a setting in the frontend so users can choose. 

Depth Buffer: 

• Fast – updates in real time
• Normal – up to 20 updates per second (depends on market activity)
• Slow – updates once every second

They nice thing as an AMP customer, you can use any of the data feeds at AMP:  CQG, Rithmic, CTS or TT.  Which ever you feel is best for you, is the one you can use.

This "unfiltered" term is used a lot in public forums, but now you know the actual, true technical function > please feel free to spread the knowledge where you see fit :)