(solution) A researcher wants to know if the number of professional development courses that a teacher…

(solution) A researcher wants to know if the number of professional development courses that a teacher…

A researcher wants to know if the number of professional development courses that a teacher completes differs based on the format that the professional development is offered (online, mixed mode, face-to-face). The researcher randomly samples 100 teachers employed in the district. Believing that years of teaching experience may be a concomitant variable, the researcher ranks the teachers on years of experience and places them in categories that represent 5-year intervals. The researcher then randomly selects 4 years of experience blocks. The teachers within those blocks are then randomly assigned to professional development format. Which of the following methods of blocking is employed here? a. Predefined value blocking b. Predefined range blocking c. Sampled value blocking d. Sampled range blocking