Affect - effect
The two words affect and effect, and various related words, are often confused. They are virtually homophones and they have similar meanings. But their grammatical use is different - they belong to different word classes.
- 'To affect' is a verb. It means 'to have an influence on', 'to cause a change in'. Examples: "Large volcanic eruptions can affect the weather"; "he was affected by the emotion in the music"; "in 1980, the country's GDP was affected by the global depression"; "drought affects a farmer's earnings". The -ing participle affecting, used intransitively, means 'moving the emotions of the reader'. It is rather less forceful in its meaning than the verb 'to impact', which is often wrongly used (see impact for advice) - so you are advised to prefer affect in academic English
- It can also mean, in rather old-fashioned English, 'to pretend (to be in favour of)'. "He affects Manchester United" would be an unlikely example of its use; but Shakespeare uses it about a King's favourites: "I thought the King had more affected the Duke of Albany than Cornwall" (King Lear). The past participle affected is more common these days. It means 'with rather careful, exaggerated ways of behaving': "he is a very precious and affected young man." The noun for such behaviour is 'affectation'.
- An effect is the noun closely related to the above. It means 'the results or influences' of something. E.g. "the effects of a volcano can be seen in bright sunsets"; "the effects of education include increased earnings"; "the effect of a drought on subsistence farmers can be fatal".
- There is also a verb 'to effect'. It is rare, except in military and sometimes political circles. It means 'to carry out' or 'to execute' an order or policy. Avoid it - unless you are in military circles. Certainly do not use affect when you mean effect.
The sentence, "Mr. Rose ... has affected several measurements and specific radiation studies" (from an e-mail), seems to be an example of the mistaken use. An 'expert' often effects measurements (~ 'carries them out', or 'measures something'). What has actually been written, affected, suggests that the expert has changed, or adjusted, the measurements. This could be a serious accusation against the professional probity of the expert concerned. A reverse error came in a letter to the Guardian from the Green Party: "[an argument for nuclear energy] ignores any determination to effect energy related emissions from the demand side." The writer presumably wants emissions to be reduced; what is written means that they will be carried out - quite the opposite of the intended meaning.
An example of better use is: "Archbishop Tutu's lecture was affecting and effective." This means that the lecturer both appealed to the emotions of the audience, and managed to communicate his purpose well.
- A witty letter in the Guardian (22/10/07) from Jerry Stuart of London asked "As nothing affects anything any more but impacts on it, what impact will this have on the verb to affect?". The next day Neville Denson of Cumbria answered "The answer is it will have no effect at all." (AWE's emboldening.)
For a common mis-spelling of an adjective, see Effective.