time or times (singular or plural)

Time until a customer comes to a store since the last customer is a waiting time. Suppose there are 10 customers in a day, we can collect 10 waiting times (e.g., 48 min, 3 min, etc.). Based on the 10 values, we can compute a variance. I don't know if when talking about variance or variation in a quantity, the quantity should be in singular or plural.

The variance in waiting time was higher for Store A than Store B.
The variance in waiting times was higher for Store A than Store B.
The variance of waiting time was higher for Store A than Store B.
The variance of waiting times was higher for Store A than Store B.

quibble

Posted 2014-06-08T06:31:47.317

Reputation: 835

Answers

I'm a statistician. "Variance of waiting time" is how I would word this and how I have seen it worded elsewhere. This is similar to other uses of variance. We say the "variance of weight" or "variance of income" etc.

So, "of" and singular.

Peter Flom

Posted 2014-06-08T06:31:47.317

Reputation: 2 320

You can use either:

The variable you are measuring is "the waiting time". The set of data you generated would be the set "of (the) waiting times". A pure mathematician would likely use the former (as posted above), a computer programmer implementing the algorithm for variance would likely use the latter. But both would understand each other.

John66NY

Posted 2014-06-08T06:31:47.317

Reputation: 1