affect effect

These 2 are quite tricky and I've tried to keep it simple with the most common usages.


(i)  effect - the noun meaning an end result

cause and effect

what effect did x have on y?

the effect of the gulf stream on our climate

sound effects

it had the opposite effect

his personal effects 

(ii) affect, on the other hand, is a verb meaning to have an influence on

she was badly affected by the death of her father
the poor summer weather will affect sales of ice cream

It is easy to see why confusion can arise: when an action affects something, it produces an effect.


(iii) another meaning of to affect and have an affectation ls the idea of putting on airs

he affected an American accent
a childish affectation
he had military affectations although he had never been in the services

RULE OF THUMB
so  EFFECT is a noun and AFFECT is a verb


affect is never a noun
(iv)  but effect can be a verb in the sense to bring about change

he effected changes in working practices

affective/effective?

almost always it will be effective

effective - the adjective meaning having the intended effect

is this treatment effective?

affective is only a psychological term as in

Seasonal Affective Disorder

affected / effected?

Most often it will be affected. This is frequently done incorrectly. Same rules (ii) and (iv) apply as for affect the verb and effect the verb. 
affected means impacted upon
effected means brought about, produced

we won't be affected
the worst affected areas
reforms will be effected immediately

Test yourself
effect/affect?

1. with immediate …………
2. the suspension would take ………… from Saturday
3. the storms may ………… ferry sailings
4. the new boss is not having much …………
5. were you ……………ed by the power cut last night 
6. ………………ive measures were taken to prevent another accident

ANSWERS

1. with immediate effect (noun)
2. the suspension would take effect (noun) from Saturday
3. the storms may affect (verb) ferry sailings
   
4. the new boss is not having much effect (noun)
5. were you affected (impacted upon) by the power cut last night 
6. effective measures were taken to prevent another accident