Explain in your own words how the effects of chance (random error) and systematic biases can be reduced in clinical trials. This question is about the methods in general, and the next question is about approaches used in the paper we are appraising. (~400 words; 20% of mark)

The effects of add-on corticosteroids on renal outcomes in patients with biopsy proven HIV associated nephropathy: a single centre study from South Africa

Explain in your own words how the effects of chance (random error) and systematic biases can be reduced in clinical trials. This question is about the methods in general, and the next question is about approaches used in the paper we are appraising. (~400 words; 20% of mark)