You are Here: Home >< Maths

# simple definition of bias in statistics ? watch

1. I've tried looking online but really complicated answers that are hard to understand are given.
2. If you mean the bias of an estimator, it is the difference between the expected value of the estimator and the true value of the underlying parameter.

Say a population has a true mean, variance et cetera, and you want to estimate these by taking a finite sample from that population. An unbiased estimator is one where the estimate, on average, gives the true population statistic (although in reality the sample statistics will vary about this number).
3. (Original post by Rinsed)
If you mean the bias of an estimator, it is the difference between the expected value of the estimator and the true value of the underlying parameter.

Say a population has a true mean, variance et cetera, and you want to estimate these by taking a finite sample from that population. An unbiased estimator is one where the estimate, on average, gives the true population statistic (although in reality the sample statistics will vary about this number).
thanks for the reply. so could I say that bias is a value that doesn't truly reflect the real population
4. (Original post by jonjoshelvey21)
thanks for the reply. so could I say that bias is a value that doesn't truly reflect the real population
If your estimator has a positive bias, say, then you expect your estimates to come out on average a bit higher than the true population parameter. Bias is a measure of how much you expect your estimator to differ from the underlying population.

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: February 15, 2018
Today on TSR

### He lied about his age

Thought he was 19... really he's 14

### University open days

Wed, 25 Jul '18
2. University of Buckingham
Wed, 25 Jul '18
3. Bournemouth University
Wed, 1 Aug '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams