Which one do I use?
I often run across sentences like this when I’m editing:
Less rhGH patients than controls reported that they lived with a partner.
The cost of an effective dose of this medication is more than the cost of that medication.
Both are incorrect. But how is a non-native English speaker to tell, when even native speakers sometimes make this mistake?
More vs. greater
You use “more” when referring to objects you can count.
More patients have this disease (100 patients) than that disease (25 patients).
You can count the patients, so “more” will always be correct.)
You can use more when uncountable things increase, too.
It costs more to give treatment A than treatment B.
Our institute has more funding than any other institute.
Used this way, cost is not countable. Actually, in this case “It costs more” really is an abbreviation for “It costs more money…” Though you can count your money (1 Euro, 2 Euros, 3 Euros…), you can’t count money itself (one money, two monies, three monies). This is always how you can tell if a noun is countable or not. In the second sentence, “funding” is uncountable (“1 funding, 2 fundings, 3 fundings,” wouldn’t make any sense).
The exception to the above rule is an uncountable noun that stands for an actual number. There are lot of implied numbers in scientific writing, so it’s important for scientists to know when to use greater instead of more:
The cost of an effective dose of this medication is greater (100 Euro) than the cost of that medication (80 Euro).
The total of A (a million Euro) is greater than the total of B (50,000 Euro).
Whenever you refer to costs or totals, they always stand for a real number. It’s built into the word, just like it’s built into percent, interest rate, population, volume, distance, weight, height, CD4 cell count, price, melting point, and the word number itself.
Less vs. fewer
Deciding when to use “less” or “fewer” is a little more difficult. Many people, including native English speakers, confuse them. But it still comes down to to whether a noun is countable or not. (Remember to use the 1…, 2… 3… trick!)
We need to use “fewer” when something countable decreases:
Fewer rhGH patients than controls reported that they lived with a partner. (1 patient, 2 patients, 3 patients…)
Our institute has fewer Swiss Ph.D.s than it did last year.
If we address the immediate problem, we will have fewer problems to worry about.
We can use “less” in all other cases: when nouns are uncountable, or when we are comparing decreasing numbers of things we can count. (This is just like above: percent, interest rate, population, volume, distance, weight, height, CD4 cell count, price, melting point, and number are all “less.”)
HIV is less easily transmitted when people are on ART.
There is less poverty in Switzerland than in many other countries.
The population of Switzerland is less than the state of California.
The flash point of paper is less than wood.