A study looks at 100 patients to see if a long-term vegetarian diet affected the outcome of iron deficiency anaemia. 50 patients had iron deficiency anaemia and 50 patients had a normal full blood count, and the authors wanted to see whether having a vegetarian diet affected the outcome. 20 of the 50 patients with a vegetarian diet also had a diagnosis of Iron deficiency anaemia. Of the 50 patients with a normal full blood count, 16 had iron deficiency anaemia.
What is the odds ratio of having a vegetarian diet? The final answer should be rounded to one decimal place.