Unit 10- Data Analysis
Bias, samples, populations, theoretical probability, experimental probability and subjective judgement.
Is it Biased
A question is biased if the results could become skewered. For example, the question "Should all cities in India implement anti-tiger measures" would be biased if the surveyors were asking six year old's in Mexico, because the six year old's would skewer the results.
Which of the following questions are biased?
Which of the following questions are biased?
Samples and Populations
A population is all the people who could be surveyed.
A sample is a small portion of all the people that could be surveyed. There are several types of samples.
A sample is a small portion of all the people that could be surveyed. There are several types of samples.
- Convenient Sample- Choosing people who are easy to access.
- Random Sample- Choosing a number of people randomly from the population.
- Stratified Sample- Dividing the population into different chunks, then choosing the same number of people from each chunk.
- Systematic Sample- Choosing people at fixed intervals from a list of the population.
- Voluntary Response- Inviting the whole population to participate, and letting them answer on their own.
Probability
Probability is the likelihood an event will occur. There are three different types of probability.
- Theoretical Probability- Based on numbers. The number of favorable outcomes over the number of possible outcomes.
- Experimental Probability- Based on past events. The probability of an event calculated from experimental results.
- Subjective Judgement- Based on feelings. A personal judgement based on emotions and feelings.
Examples- Theoretical Probability- Brian is going to roll dice for a sword. He says that his lucky number is seven, because when rolling two dice seven is the number most likely to come up.
-Experimental Probability-Brian is still rolling dice for a sword. This time, he says that his lucky number is four, because he kept on getting the number four last time he rolled dice.
- Brian is trying once more to win a sword at dice. He says that he will choose the number nine because he was nine years old when he decided to become a knight, and seven and four didn't seem to work out.
Note: Brian never got that sword. Instead he lost all his money gambling for it and had to use a second rate mace he found in some garbage pile.
-Experimental Probability-Brian is still rolling dice for a sword. This time, he says that his lucky number is four, because he kept on getting the number four last time he rolled dice.
- Brian is trying once more to win a sword at dice. He says that he will choose the number nine because he was nine years old when he decided to become a knight, and seven and four didn't seem to work out.
Note: Brian never got that sword. Instead he lost all his money gambling for it and had to use a second rate mace he found in some garbage pile.