Each trimester a business school offers extra tuition assistance to students. Administrative staff who organise this extra tuition want to investigate what proportion of students are aware of this service. Staff have proposed two sampling strategies, listed below.

a) The first sampling strategy is to email a random sample of business school students and ask them if they are aware of the extra tuition assistance.

What type of bias may this suffer from? Briefly explain your choice in the context of this question.

b) The second sampling strategy involves administrative staff placing a notice of the extra tuition service in the student lounge on campus. Students who take a selfie photo of this notice and send it in to the business college will get a free business college backpack.

What type of bias may this suffer from? Briefly explain your choice in the context of this question.