Online courses are as effective as in-classroom instruction because they allow students to work at their own pace. Students can concentrate better from their own study environments and have much more direct access to their professors via email and chat than they might in an overcrowded classroom. They don't have the distractions of other students around them and can devote one hundred percent attention to the learning at hand.
Online courses are basically a scam, they create an environment that is not learning orientated. Why do we look at online degrees with such skepticism? The reason why is because they hold no weight. How many great schools offer online programs? It is a waste of time and it exploits people who need an education and can't get it through traditional measures.
No, online courses are not as educationally effective as in-classroom instruction. Online courses have several disadvantages. In a classroom setting, you can raise a hand the minute you have a question and get an immediate response from the instructor. If you need further clarification, that instructor is still there in the front of the room. With classrooms, you can have a dialogue with people who have perspectives and ideas different from your own. You can exchange viewpoints and have conversations about work assignments. With online courses, you lose something by not having the face to face discussions and conversations that lead to deeper understanding of assignments.
While online courses can certainly be effective educationally, I believe that they do not offer the same level of education that face-to-face interaction can provide. Having the ability to ask questions and get clarification from a live instructor generally gives you a better grasp on the subject matter than learning with online courses.