In this paper we present a study aimed at assessing biases in conditional probability reasoning in prospective secondary school and high school mathematics teachers. We analyze responses to 7 items taken from the CPR (conditional probability reasoning) in a sample of 196 last year mathematics students and Máster students, finding a high incidence in both groups of the time axis fallacy, transposed conditional, confusion between conditional and compound probability, base rates fallacy, and incorrect conceptions of independence. We conclude that there is a need to prepare prospective teachers better to prevent them from transmitting these biases to their students.
Biases; Conditional Probability; Prospective Secondary Teachers; Assessment
