Wanda reads a research report that says that a recent study found a correlation between oatmeal and cancer: the more oatmeal a person eats, the greater the risk of being diagnosed with cancer. Wanda immediately concludes that she needs to stop eating oatmeal for breakfast. What is wrong with this conclusion

The thing wrong with the conclusion is that the conclusion was made without data.

Explanation:

Data from scientific researches can be group into quantitative or qualitative researches, qualitative data is one that is non-numerical, and at best organizes and characterizes, e.g, eye colors as brown, blue, yellow e.t.c, while quantitative data are numerical data.

The type of study described here is a correlation study, and correlation studies are almost always quantitative studies, hence, data should be available in the report on the exact quantity of oatmeal that puts one at risk of development of cancer. Knowledge of this, will influence decision as to what the safe dosage of oatmeal is to be taken. Therefore, Wanda's stoppage of consumption of oatmeal is made without data support, and this  is a wrong conclusion.

Secondly, scientific researches are considered accurate can be used to make decisions if they are reproducible. Wanda cannot trust the validity of a single report to make her decision, there must be at least two different researches with the same result before decisions such as this can be made.