A reader writes:
I keep seeing this: “lacked considerably behind” when what is meant is “lagged considerably behind.”
When I went looking, I also found many examples of lacking where the context calls for lagging. Here are a few:
Incorrect: Bad WPO ranking on most pages [are] lacking behind the top US healthcare sites
Correct: Bad WPO ranking on most pages [are] lagging behind the top US healthcare sites
Incorrect: Africa is clearly lacking behind [in foreign investment].
Correct: Africa is clearly lagging behind [in foreign investment].
Incorrect: Good research lacking behind fitness promises
Correct: Good research lagging behind fitness promises
The meaning of the verb lag in the idiom “to lag behind” is “to fail to keep pace with others.”
Usually, the behind that follows lagging is a preposition that takes an object:
One very controversial topic recently is how America is lagging far behind other nations in terms of quality of education.—Business Today.
Sometimes “lagging behind” is used as a phrasal verb:
U.S. lagging behind on gender equality.—CNN.
The verb to lack means “to be deficient in quantity or degree.” For example:
Customers with mental illness are lacking services due to decreased funding available to the local CMH.
When your intended meaning is “to fail to maintain the desired speed of progress,” “to slacken the desired pace from weakness or sloth,” “to hang back,” “to fall behind,” or “to remain in the rear,” the idiom you want is “to lag behind.”