Tuesday, August 29, 2006

Why it seems like everyone goes to college

A minor detail that I found interesting in the map from the previous post on Starbucks and McDonald's, is that I did not know that KFC and Taco Bell had higher revenues than Starbucks. I expected Starbucks to make more money than either because I know a lot more people that spend a lot of money at Starbucks as opposed to KFC or Taco Bell.

The problem with my logic is an idea called selection bias. This is where you come to the wrong conclusion due to the fact that the sample of people you know or study does not represent the population as a whole. So just because I don't know many people who eat at KFC or Taco Bell, that might just mean that the type of people I know don't eat there as much as the general population.

Another example of this bias is how students at Walker are surprised to find out that only 60% or so of high school students go to college right out of high school. There is a selection bias at work here since almost everyone you know at Walker or other Cobb county schools plan on going to college, but that does not represent the country as a whole. If you went to an inner city public school or lived in a very rural area, that percentage may seem high instead.

Can you think of any other cases where you had a misconception due to selection bias? Or perhaps a common selection bias amongst Walker students or people you know?


Anonymous said...

I can think of another bias with college and Walker School students. Throughout high school we are taught to go to the college of our dreams and to reach as high as we can. What we don't realize is that kids at other school are not pushed as hard as we are, and colleges that students at our school barely imagine going to are the only shot for other students. For example, for many students at Walker, it is considered a "let down" if they go to KSU, while it is the "norm" to go to an out of state, high profile, college. Not saying that going to KSU is unacceptable to any person, the school has been growing over the past year in not only numbers but also academics, but at Walker many students look at KSU as a last resort, when kids from other neighboring schools go there first-choice.
-Sara Diehl

Anonymous said...

one misconception that i can think of due to a selection bias is the percentage of high schoolers who own their own car. Here at walker, it is extremely rare to find someone who does not own a car. However, the national percentage of 16-19 year olds who do have their own vehicles to drive is 41 percent(washington post). This is less then half, however, at walker almost everyone does.


Anonymous said...

One example of a selection bias at our school is the amount of motivation that exists within our students. Everyone at Walker strives to go their dream school and become someone successful in the future. Walker students push themselves to the limit even though they are not required to. We don't have to take honors and AP classes but we bear the increased workload in order to increase our chances of getting into our dream college and also to push ourselves academically. Many students, including myself, take AP classes because they have an interest in that subject. This is an example of students wanting to increase their education and gain knowlegde. I worked at a restaraunt near my house this summer and all of the other employees were from public schools. They were classes and getting grades on a scale of just getting by. There was no strive for excellence in any academic area. They told me that school was over rated and that they had no future plans. These kids had no aims or goals in life and all they wanted to do was "eek" through life making minimum wage and having to life week-to-week financially. I assumed that about every student had dreams of becoming a success one day and making a lot of money, but there are many kids out there that lack the motivation and self-pride to make an effort and to amount to something in the long run.

-Chris Templin

Anonymous said...

When ipods first became popular a couple years back, i found the trendy gadget and high price tag unappealing. Today, I and a large majority of my friends at walker own an ipod or mp3 player. The assumption that most people own ipods is an unquestionable Walker selection bias. According to cnetnews.com, recent studies have shown that only 11% of the US population owns an ipod. While this still constitutes for 22 million American adults, eleven percent is relativley small compared to the percentage owned by Walker students.