Read the article “Prenatal Diagnosis of Placenta Accreta: Sonography or Magnetic Resonance Imaging?”

1. Is this study a prospective study or a retrospective (case-control) study? Explain your answer.

2. Which is the “treatment” group in the study, and which is the “control” group? Explain your answer.

3. Determine whether or not there is an association between correctly identifying placenta accreta using sonography vs. magnetic resource imaging (MRI).

4. Decide whether you should use an odds ratio or relative risk, then calculate the one you chose. Determine if the odds favour sonography or MRI for correctly identifying placenta accreta.

**Subject Mathematics Applied Statistics**