I do medical transcription and always seem to have trouble with the use of the word effect and affect. Sometimes it is very obvious.

The following sentence I questioned:

I have enclosed portions of a chapter from Baker's Textbook of Clinical Neurology, which I believe you will find of significance in discussing the origins of cerebral palsy and its affect on motor function and gait.

Is this correct?
I have enclosed portions of a chapter from Baker's Textbook of Clinical Neurology, which I believe you will find of significance in discussing the origins of cerebral palsy and its affect on motor function and gait.

In this case I'd use 'effect', (I find this tricky too!)

ef·fect n.

Something brought about by a cause or agent; a result.
The power to produce an outcome or achieve a result; influence: The drug had an immediate effect on the pain. The government's action had no effect on the trade imbalance.
A scientific law, hypothesis, or phenomenon: the photovoltaic effect.
Advantage; avail: used her words to great effect in influencing the jury.
The condition of being in full force or execution: a new regulation that goes into effect tomorrow.

Something that produces a specific impression or supports a general design or intention: The lighting effects emphasized the harsh atmosphere of the drama.
A particular impression: large windows that gave an effect of spaciousness.
Production of a desired impression: spent lavishly on dinner just for effect.
The basic or general meaning; import: He said he was greatly worried, or words to that effect.
effects Movable belongings; goods.

af·fect1 tr.v.

To have an influence on or effect a change in: Inflation affects the buying power of the dollar.
To act on the emotions of; touch or move.
To attack or infect, as a disease: Rheumatic fever can affect the heart.
Found this:

Affect is a verb. Look at the a in affect and think "action." The movie affected her greatly.

Effect is a verb or a noun. It's most commonly used as a noun. The movie had an effect on her.

As a verb, effect means to bring something about, especially a change. Encarta World English Dictionary offers this example: They effected their escape through a rear window.

But there's no difference between saying that and saying "They escaped through a rear window," so you should always think twice before using effect as a verb.
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Hi folks,

I really love this site, it reminds me of the apostrophe protection society blog. Very interesting!

Anyway, I believe there is a very simple method to differentiate between effect and affect.

When used as nouns, the difference is pretty obvious.
An effect is a result of an action, while an affect is a feeling or emotion.

When used as verbs:
Effect is an active verb: 'The government effected swift decreases in the unemployment level.'
Affect is a passive verb: 'The unemployment level was positively affected by new government policies.'

If you have any trouble figuring out the difference between the active and passive tense, the trick is the word by. Usually, if there is a clause at the end of a sentence starting with by, the verb is passive. In the first sentence, the subject (government) is the actor. In other words the subject carried out an action. In the second sentence, the subject (unemployment level) is acted upon by a different entity.

However, affect can also be used in an active sense, but the context is different, ‘Mike affected an English accent to disguise his Irish roots’.

This of course is only my humble opinion, put together in the days before Google. So, I’d like to hear any comments on my theory, good or bad. If any of my sweeping grammatical statements are incorrect, I’ll have to shift the blame onto my English teacher of yore.

It is a verb meaning "have an effect on", so it has to be the verb "affect".

It occurs without "the" or "an" or "no" (or other determiners), so that's another clue that it's probably not the noun "effect", meaning something like "result".

That drug can have a very powerful ______ (affect=have an effect on?, effect?) on the nervous system.

Nothing you say can _______ (affect=have an effect on?, effect?) my decision.

That joke did not have the intended ______ . (affect=have an effect on?, effect?)

The stroke he had years ago still continues to _______ (affect=have an effect on?, effect?) his speech.

(Answers: effect, affect, effect, affect)

Emotion: geeked

You've heard of "causes" and "effects"? Well, strangely enough "effect" is almost never a verb unless it means "cause"! And that happens very rarely.
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I've always had a problem with this too! Nice to see the definitions though!
 hitchhiker's reply was promoted to an answer.
The pedant in me has to point out that "affect" can be used as a noun too, meaning a particular emotion.
But yeah, generally you're safe if you use "affect" as a verb and "effect" as a noun, unless you're trying to effect a change in your affects.Emotion: wink
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Kitkattail - You're a tough one, valid point! Good to have you with us..
Aww... I feel all warm and fuzzy inside!
By the way, I must take a moment to express how awesome this site is. I just came across it today, and I'm having way too much fun responding to all these questions. I just hope I'm not being a little overzealous. Do let me know if I become irksome, will you?
I think your sentences, in effect, have a great effect on this forum? Would this sentence be correct?
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Yes yes, that's right.
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