Diction and Interpretation in Academic Writing

Consider the following sentence:

"The student's essay was filled with *anecdotal* evidence, weaving personal stories to support her arguments, but lacked the *rigor* of more scholarly research."

In this context, the narrator's choice of the words *anecdotal* and *rigor* conveys a particular attitude towards the student’s writing. Based on the author’s use of these specific terms, what can be inferred about the narrator's perspective on the effectiveness of the essay?