# Why Literacy "Rate"?

I recently had a discussion with a friend, and he was using a phrase repeatedly which said "Conversion Rate vs Time". I pointed out to him that Rate already has the time factor, so you don't have to say Rate vs Time, but he then pointed me to the Wikipedia page for Rate

The most common type of rate is "per unit time", such as speed, heart rate and flux. Ratios that have a non-time denominator include exchange rates, literacy rates and electric flux.

Which is fair enough, but it did leave me confused (for the first time so many years) by the term Literacy Rate. I never realized it till now, but why do we append Rate to Literacy?

Is Literacy alone not enough to define the metric which we now call Literacy Rate? Why do we use Rate? What does Rate signify in this scenario?

• @Josh61 - You could probably say literacy percentage and (usually) be understood, but it I suspect it would cause some people to do a double-take. This is because literacy rate is such a well-established expression for describing the extent of literacy in a society that using a different (though perfectly logical) term would not be expected. Commented Feb 24, 2015 at 8:10
• We talk about the birth and death rates. They are, for example, the number of live births per 1,000 of population - in a given period of time, usually a year. So time does come into it, albeit a long chunk of time. The two more immediate factors are birth and population. Literacy rate is a bit like those without the annualised element. But heart rate versus time is not without meaning, for example, for a graph which plots a patient's heart rate daily for a month.
– WS2
Commented Feb 24, 2015 at 10:14
• Simple question: Why not? What's wrong with using "rate" in that context? Commented Feb 24, 2015 at 13:11
• I'm voting to close this question as off-topic because it looks like a pedantic peeve Commented Feb 24, 2015 at 16:04
• @FumbleFingers and what is not a pedantic peeve of English language here? Cases in Point Commented Feb 25, 2015 at 6:18

Literacy refers to the quality or state of being literate, esp. the ability to read and write. Literacy rate refers to the percentage of people who are able to read and write vs those who are not.

• The condition or quality of being literate, especially the ability to read and write

Literacy rate

• (social studies) the percentage of people who are able to read and write

Rate:

• A measure of a part with respect to a whole; a proportion: the mortality rate; a tax rate.

( TFD)

Ngram : literacy rate, ratio, proportion, percentage.

• Rate is the term usually applied to division-based comparisons of two disparate measures (classically distance / time, but not restricted to this: speed / time; temperature / time; distance / stretching force ...). The term usually applied to division-based comparisons of two measures of like variables (cows : bulls, pupil/teacher) is ratio. [a measure of the relative size of two classes expressible as a proportion: the ratio of boys to girls is 2 to 1.; Collins]. Percentage, proportion, quotient ... are also used. But collocations with these terms are idiosyncratic. Commented Feb 24, 2015 at 10:14
• @EdwinAshworth That is very well explained. But it does suggest to me that literacy ratio may be as valid as literacy rate, and perhaps explains why I have heard it used.
– WS2
Commented Feb 24, 2015 at 12:55
• @WS2 - "Literacy ratio" would run a serious risk of being interpreted as the ratio of literate to illiterate people. Commented Feb 24, 2015 at 13:13
• @HotLicks Expressed as a percentage, yes you are right, it would be.
– WS2
Commented Feb 24, 2015 at 13:48