What is a word which refers to any number of items that exist as measured quantities in something? This is like measurand, similar to how operand is some kind of modifier to an overall o.
The word "measure" itself can mean a measured quantity. From NOAD:
2 a standard unit used to express the size, amount, or degree of something: a furlong is an obsolete measure of length | tables of weights and measures.
• a system or scale of such units: the original dimensions were in imperial measure.
• a particular amount of something: a measure of egg white as a binding agent.
• a standard official amount of an alcoholic drink as served in a licensed establishment.
Absent context, terms like datum ("a measurement of something on a scale understood by both the recorder (a person or device) and the reader"), number, statistic ("a single item in a statistical study"), measurement ("magnitude (or extent or amount) determined by measurement"), and previously-suggested measure and measurand are as good as any.