An example of a Type I error is when a researcher concludes ______.

A) an effect does not exist when it actually does
B) an effect exists when it actually doesn't
C) groups do not differ when they actually do
D) groups are the same when they're actually different

A Type I error occurs when a researcher concludes that an effect exists when it actually doesn't. Option A describes a Type II error, whereas options C and D describe incorrectly concluding no difference or similarity between groups, which may or may not be a Type I error depending on the context.