I am looking for an online statistics course to take this summer to fulfill a prerequisite for the coming fall. Any advice?
Taking care of prerequisites can prove tricky at times. This is why I'm happy that you are starting early to complete your statistics requirement. Finding a class is not the difficult part. If you don't do your research and ask the right questions, frustration may occur when a school refuses to accept the class you've just spend weeks completing.
To make sure you don't run into any obstacles, contact the Admissions and Records department of the school you are attending this fall. Ask if the statistics course has to be taken from a specific institution to be accepted for credit. It's always helpful to write down the name of the person you speak with and the advice they give you during the conversation. These notes are useful when talking to another person who offers conflicting information. Your particular school may offer a statistics course on campus or online and prefer that you take the class from them.
If your college says it's an acceptable option to take the class through an outside school, ask for recommendations. Accreditation is a key factor in choosing a course provider. You want to take your class from a reputable program that your school will acknowledge. Ask before you sign up for anything. This is your education; so don't hesitate to do a little research before diving in headfirst.