Can you help me find some SOURCES OF BIAS on my survey?

-Our high school has a maximum of 800 students in total





-I surveyed 200 people in my high school





-This came up to: 40 random students from each grade (grade: 7, 8, 9, 10 11) (40 x 5=200)





-I randomly asked students in our school cafeteria to do my surveys





THIS WAS MY SURVEY:





Which of the following COLD beverages do you drink the most?





a) Water


b) Juice


c) Soda


d) Milk


e) Energy Drink


f) Other





Which of the following HOT beverages do you drink the most?





a) Coffee


b) Tea


c) Hot Chocolate


d) Other





WERE THERE ANY SOURCES OF BIASES INVOLVED IN MY SURVEY? Please give me AS MANY as you can find, or think of-- taking in mind the place and stuff we did our survey in!





(10 points for most helpful answer!)

Can you help me find some SOURCES OF BIAS on my survey?
If the term bias applies to this your survey results may show a bias towards what the consumers can afford. Many students may drink water because they don't have money for juice. I do not think you clarified if the drinks were free or paid for
Reply:I think everyone enjoys a cold beverage, but "NONE" should have been a choice, especially in the hot beverage question.





"Other" is too broad of a term. You could possibly benefitted from a write-in, again, especially in the hot question. The cold question covers just about everything except those drinks like gatorade, propel. smoothies or capri sun which do not fall under any of the choices listed. With a write-in, you might have found that more kids are drinking capri sun than are drinking milk.





As you first answer stated, maybe it's about affordability. Your question might have asked which drinks they like and not which ones they drink. They might not like the drink packed in their lunch at all, or maybe they'd prefer a soda over milk.





To me, there does not seem to be anything that directs a preferred response.





Those are all of my ideas.





Enjoy your results.
Reply:1. It is a convience sample. Only students in the cafeteria are asked instead of all students which are chosen from a simple random sample using the table of random numbers.





2. Depending on what you are trying to determine, whether it is the most popular cold and hot beverage in all high schools or your own high school, can affect the validity of your survey. If it attempts to determine for all high schools, it is an unrepresentative sample.





3. Nonresponse bias, students may refuse to answer survey. This can alter results.