Question

Tammy conducted a survey to find the favorite subject of the students at her school. She asked 25 students from her math class what their favorite subject is. Tammy concludes that math is the favorite subject of the students at her school because 60% of the students in her class like math.
Use at least two sentences to explain why tammys sample may not be valid. Make sure to use facts to support your answer.

Answer 1

Tammy's sample may not be considered valid because, on the first hand, it is said that she only asked students from her " Math Class". 
If she wants to have a survey to find out the favorite subject of the students at her school, she must conduct a survey involving all the students in her school, not just in her class. What she did is just subjective. She should use a tally listing the different subjects and compare the number of students per subject. This way, she can have an objective representation of the least liked subjects and the most liked subjects of the students on her school.
Illustrating her survey through statistics may be more reliable and valid because it shows frequencies in which she can calculate easily and accurately the percentage of  the number of students per subject, in a more objective manner.