I've run across two sentences recently that confused affect and effect in a similar way:
- While the university doesn’t yet know what schools, programs and departments might be effected [by budget cuts], leaders there are moving quickly.
- BSH plans to phase out sales of its 27-inch, front-load washers and dryers by the end of the year, and effected employees will stop working this spring.
Both of the underlined words should have been affected, as in "to have an effect on." The writers could have puzzled this out by turning the sentences around, perhaps. The budget cuts will affect schools, programs and departments. Closing down the production line will affect employees. That's how I would figure out the right spelling.
Some people like to use the mnemonic RAVEN: Remember Affect Verb Effect Noun. Of course, effect can be a verb also, meaning "to bring about." But most of the time, if the word you want is a verb (or a verb form used as a modifier, as in the second sentence), use affect.