There is a theoretical problem with the application of traditional teaching methods to online courses because online courses may have no upper size limit. Daniel Barwick noted that there is no evidence that large class size is always worse or that small class size is always better, although a negative link has been established between certain types of instruction in large classes and learning outcomes; he argued that higher education has not made a sufficient effort to experiment with a variety of instructional methods to determine whether the large class size is always negatively correlated with a reduction in learning outcomes. Early proponents of Massive Open Online Courses (MOOCs) saw them as just the type of experiment that Barwick had pointed out was lacking in higher education, although Barwick himself has never advocated for MOOCs.