Quick post to clear up some terminology. But first, an analogy to clear up my thinking:
Analogy
Temperature control is a big part of brewing beer. Throughout the brewing process I use a thermometer to measure the temperature of the soon-to-be beer. Because I take several temperature readings throughout the brewing process, one brew will result in a list of a half dozen temperature readings. For example, I take a mash temperature, then a sparge temperature, then a fermentation temperature. The units on these measurements are always in Fahrenheit, but their interpretation is different.
The Rub
In this example, I would call the thermometer a "probe". The set of all temperature readings share a "data type". Each temperature reading is a "measurement" which is stored in a given "field".
At the SFO workweek I uncovered some terminology I found confusing. Specifically, we use the word "probe" to refer to data we collect. I haven't encountered this usage outside of Mozilla.
Instead, I'd suggest we call histograms and scalars "data types".
A "probe" is a unit of client-side code that collects a measurement for us.
A single "field" could be be a column in one of our datasets (like normalized_channel).
A measurement would be a value from a single field from a single ping (like the string "release").