Some words are very frequently confused. Sometimes, this makes the writer’s intent unclear. In other cases, the meaning of the sentence may be clear, but it’s still distracting to those readers who know the difference. So it matters.

This little blog entry focuses on words that commonly appear in scientific writing and that are often confused or misused. There is a longer list of words commonly confused in general writing here: http://writing2.richmond.edu/writing/wweb/conford.html. By all means consult this source in addition to this post.

Principle/principal: “Principle” is a noun that means a fundamental rule, truth or law. It is never an adjective. The adjectival form of this word is “principled“. “Principal” can be either an adjective or a noun. As an adjective, it means “main” or “most important”. So all of you PIs out there are “Principal Investigators”. I hope that you are also “principled investigators”, but “Principle Investigator” would mean someone who carries out research into principles, which I suppose might be applied to ethicists, although it would be unusual to do so. As a noun, “principal” can have one of two meanings: It can mean the main person involved in some affair or transaction, as in “the principal in a lawsuit”, who might be the main plaintiff or defendant, or it can be the title of the leader of an educational institution, e.g. the “Principal of Queen’s University”.

Adapt/adopt: A thing that is adapted is changed to suit some particular purpose. For example, a figure that was adapted from a source was not just copied. Some details of the figure were changed, or else the original was used as a model for a new figure that still retains some resemblance to the original. On the other hand, something that is adopted is just used as is, without modification. You can, for example, adopt the procedure of Smith et al. (1902), which means that you used their procedure exactly as they described it. You can also adapt Smith et al.’s (1902) procedure if you need to change it to use it in a new context, or to work with a different set of instruments, etc.

Affect/effect: This pair can be confusing because both of these words can either be a noun or a verb, but with different meanings. I’m going to focus here on the most common uses of these words in scientific writing. If you’re a psychologist, you’re going to need to do additional reading on this topic because in that discipline, the noun forms of these words have highly technical meanings that you simply have to get right.

Almost always in scientific writing outside of psychology, you’re going to use “affect” as a verb and “effect” as a noun. If you just remember that, you should be in good shape. The verb “affect” means “to produce an effect in”. (Note the use of the noun “effect” in the definition of the verb “affect”.) So, for example, the weather affects the timing of plant flowering. The noun “effect” designates a consequence of some causative event or agent. Late flowering is an effect of cool weather. Similarly, we talk of cause and effect, not cause and affect, unless you’re a psychologist.

Complimentary/complementary: In scientific writing, you want “complementary”. “Complimentary” refers to receiving praise, or being given something free-of-charge, as in “complimentary drinks”. “Complementary” has the sense of one thing completing another. Thus we have complementary angles, complementary base pairs, etc.

Infer/imply: All of the words we have looked at so far had similar spelling. This pair falls into a different category of words that are semantically related. Inferring is a logical deduction made by a person. Note that a person infers something. Lately, I’ve been noticing people using infer when they should be using imply. To imply something is to suggest it. Data can imply a particular conclusion. But only a person can infer that the data implies something. A person infers. Data implies.

Roll/role: Roll has to do with the action of rolling. For example, one can roll dice, or roll across the countryside in a car. A role, on the other hand, is a part that something plays. So mitochondria play a central role in the energy metabolism of a cell, for example.

Refute: This word isn’t a member of a simple pair, but lately I have noticed it being misused quite a lot. “Refute” has exactly one meaning: it is to prove an argument or hypothesis wrong. Note the word “prove”. To refute something is not merely to argue against it, or to provide a counterargument, or to present contradictory data. If you have refuted a hypothesis, it’s dead. It’s a very strong word, and rarely applicable. But good for you if you have managed to refute something. It’s probably a significant achievement. If it’s still at the stage where the thing is debatable, then you need a different word. It’s hard to give specific advice here, because there are many possible nuances, but here are some possible phrases you might use: “argue instead/against”, “provide a counterargument/rebuttal”, “reply”, “respond”, “cite as evidence against”, “deny”, “contradict”, “dissent”, “reject”. The variety of nuance in just these options hopefully suggests one of the problems with misusing “refute”: if it’s clear you don’t actually mean that something was conclusively disproved, what do you in fact mean? If you’re tempted to use “refute”, I would strongly suggest that you think carefully about what you really mean, and then use plain language, which may involve a complete rewriting of your sentence. For example, “Jones and Wang (2001) refuted Amato and Sveshnikov’s (1998) hypothesis”, if it doesn’t actually mean that they disproved the hypothesis, might be rewritten in any of the following ways, among many others, depending on what you’re trying to say: “Amato and Sveshnikov’s (1998) hypothesis was contradicted by Jones and Wang’s (2001) interpretation of the data”; “Jones and Wang (2001) showed that Amato and Sveshnikov’s (1998) hypothesis was more plausibly consistent with…”; Jones and Wang (2001) argued that Amato and Sveshnikov’s (1998) hypothesis was incompatible with…”

Delivery of a clear message requires clear language, and that means using the right words to express a thought.