Just a word for those who confuse "then" for "than." They are not interchangable.
Before I retired, I worked for a university professor who received his Ph.D. from a renowned California university. He consistently made the same grammatical error. I do not attribute this mistake to ignorance but possibly to the way some hear the words.
"THAN" is a word used for comparison. "THEN" is a word related to time. Please, if you are going to author articles, find a good proofreader who is a stickler for grammar and spelling. Your opinions will be all the more appreciated.