Affect vs. Effect
Usually effect is a noun and affect is a verb.
The recall had a negative effect on sales.
The recall will affect sales negatively.
Effect is less commonly used a verb.
The plan will effect a change.
Affect as a noun will generally not occur in fiction writing.
Affected vs. Effected (Affecting vs. Effecting)
Affected means created an effect on.
Affected has severeal meanings and is worth looking up to confirm appropriate usage.
(Affected can also mean inclined or artificial).
Effected means executed, or brought about something.
The oil spill adversely affected wildlife.
The moon is affecting the tides.
The boy was affected toward her.
His affected accent was annoying. (Insincere).
The government effected a recovery plan.
The campaign is effecting change.
Affective vs. Effective*
Effective is an adjective for having the desired effect and is commonly used.
Affective can be a medical term referring to emotions and is uncommonly used.
An affective person has the ability to influence a person, or a group of people, in the way they think, feel and act. This use is rare.
The drug created affective symptoms.
She is an affective saleswoman.
His mother's words were affective enough to change his mind.Effective communication is key.
His presentation was effective.
*Affective means to alter (starts with a). Effective means efficient (starts with e).
Affectively vs. Effectively
Affectively means something has been altered.
Effectively means efficiently, or according to the purpose.
He effectively ended the conversation.
He walked affectively because of the pain.
Affectation vs. Affection
An affectation is a pretense. (Behavior that is artificial and designed to impress).
Affection is a feeling of fondness.
Affectation is often used to refer to a physical attribute, even if it's not artificial. While, it's technically not correct, the usage is so common, the meaning of the word is changing over time.
His beard was an affectation she did not care for.
He showed affection to his daughter.
He was very affectionate.
Efficacy is whether it works or not or whether it has that capacity.
Efficiency is not whether it works, but how well it works.
Efficient means done in a way that is least difficult, complicated, costly. A better way.
Efficacious means having the desired result or effective, does not mean more efficient.
If you see one of these words, it's best to look it up just to ensure you're using it appropriately.
I have an affective disorder. I feel compelled to determine the correct use of affectation. I assure you my interest in grammar is not an affectation. I truly wish to know the answers to such questions. This disorder has effectively halted all forward progress in other areas of my life and the negative effects are numerous. My husband very affectively offered me some affection in an attempt to effect a distraction. His efforts were temporarily efficacious. But in the future, I must find a way to supress my disorder, or my efficiency will be affected.