Making comparisons

We generally compare things in one of two ways. To choose the correct way, we need to choose whether we are comparing a thing with a similar thing, or with a standard or quite different thing. But authors – including most native speakers - commonly mix them up.

The rule is actually simple. When comparing a variable to a similar variable, we use ‘-er than’ eg. ‘(variable) X is faster than (variable) Y’.

Think of the running speeds of Usain Bolt, Michael Johnson and Danny Devito. How would we compare them? Bolt and Johnson are both fast, but one is faster. So we would say:

Usain Bolt is faster than Michael Johnson.

We would not say:

Usain Bolt is fast compared to Michael Johnson.

- because the difference between them is minor.

When we compare a variable to a standard, or to something that is quite different in the characteristic we are comparing, we use ‘compared to.’ The pattern is ‘(variable) X is fast compared to (standard or different) Y’. Thus:

Usain Bolt is fast compared to Danny DeVito.

Note that we have some latitude in deciding whether to consider ‘Y’ a variable or a standard - it depends on the context. Accordingly, both of these are suitable:

Usain Bolt is faster than most people.

Usain Bolt is fast compared to most people.

The difference is that ‘faster than’ emphasizes the degree of difference, while ‘fast compared to’ emphasizes the fact that there is a difference.

More than half of the papers we edit contain inappropriate comparisons. This simple guide should help you get them right every time.