15th February 2024

Researchers recruited participants to investigate the role of the COVID-19 vaccine in preventing supra-added bacterial pneumonia.

Researchers recruited participants to investigate the role of the COVID-19 vaccine in preventing supra-added bacterial pneumonia. They have identified 1,000 participants, 600 of whom have received the vaccine and 400 who have not. These participants were followed up for two years, and patients were separated into three groups: patients who had gotten Staph. Aureus pneumonia, other bacterial pneumonia or no pneumonia. 

Which of the following statistical tests is most appropriate to identify any significant differences between the groups?