Copyright

Biased & Unbiased Estimators: Definition & Differences

Biased & Unbiased Estimators: Definition & Differences
Coming up next: Finding Confidence Intervals for Proportions: Formula & Example

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
 Replay
Your next lesson will play in 10 seconds
  • 0:02 What Is Bias?
  • 0:55 Difference Between…
  • 1:48 Conceptual Example
  • 2:47 Mathematical Example
  • 3:49 Lesson Summary
Add to Add to Add to

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Timeline
Autoplay
Autoplay
Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Kevin Newton

Kevin has edited encyclopedias, taught middle and high school history, and has a master's degree in Islamic law.

When dealing with statistics, you've probably heard about why it is wise to avoid biased estimators. However, as this lesson proves, sometimes a biased estimator can be pretty useful—if you know how to use it.

What Is Bias?

While we would prefer that numbers don't lie, the truth is that statistics can often be quite misleading. For that reason, it's very important to look at the bias of a statistic. Bias is the distance that a statistic describing a given sample has from reality of the population the sample was drawn from. Now that may sound like a pretty technical definition, so let me put it into plain English for you. If you were going to check the average heights of a high school by looking at a sample of 15 students, you wouldn't just call for members of the basketball team. That sample would not be reflective of the heights of everyone in the school because basketball players tend to be tall. In this lesson, we're going to look at the difference between biased and unbiased when trying to make estimations based off of statistics, as well as to look at two different examples of bias.

Difference Between Biased and Unbiased

As you might have imagined, statisticians like to avoid bias when they can. In fact, they would often rather work with unbiased data, which is to say a sample that eventually corresponds to the true nature of the population size. In plain English, if the real average height for a high school is 5'5'', then a statistician wants a sample that will give her a sample average height of around 5'5''. However, that doesn't mean that unbiased is always better than biased. In fact, when we can't find a perfectly accurate and random unbiased sample, a biased sample can still prove to be pretty useful. However, there is a catch. For us to get any real use out of a biased sample, we had best know how it is biased and just how much of a bias there is. To see how this looks, let's take a look at a couple of examples.

Conceptual Example

The first example I want to give you is completely conceptual, meaning that we won't be using numbers to prove it. Let's assume that you are up to bat during a baseball game. You're right-handed, but you've got a problem. You've hit three foul balls in a row! However, the performance of those foul balls can be called biased - each lands just foul of left field. You know that if you can straighten out your swing that you'll be able to hit a home run, but how can you use the information you've got to do so? If you understand baseball and the idea of a biased performance, it's simple.

To unlock this lesson you must be a Study.com Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back
What teachers are saying about Study.com
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create An Account
Support