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Samples and Surveys (Bias (Definition (Prejudice in favor of or against…
Samples and Surveys
Bias
Definition
Prejudice in favor of or against one thing, person, or group compared with another, usually in a way considered to be unfair.
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Example of bias
When collecting a sample from a population of parents that have kids in Chandler and Alden if taxes should be increased to build new schools for K-5. These parents will most likely say yes because their kids will be affected for the better by these school improvements.
Vocabulary
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Factors:independent variable,is an explanatory variable manipulated by the experimenter
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Sampling Errors
Convenience Sampling
Definition: Using an easy access population to gather a sample
Example: Gathering a sample from the Duxbury High School track team for the fastest mile, because they are the easiest team to get data from.
Voluntary Sample
Definition: Consists of responders who request to be involved in the population Example: a radio station taking a poll and the callers are requesting to be involved
Undercoverage
Definition: Occurs when some groups are left out of the sample choosing process.
Example: When collecting data about who bought tickets to the Duxbury High School football game at Gillete you collect a sample from students and parents but leave out the elderly. Including the elderly in the sample would be under coverage.
Non Sampling Errors
Wording Bias
Definition: when confusing or leading questions encourage bias. Example: When the question being asked to a sample is biased towards a certain part of the sample. Asking
Response Bias
Definition: A pattern of incorrect responses in a sample. Example: When people are being asked if they wear their seat belts every time they drive , by a police officer in an interview they will say yes even if they don't.
Non-Response
Definition: When the an individual needed in the sample can't be contacted or refuses to give their opinion
Example: Needing all opinions of the teachers at school about salary, but one teacher won't share their salary amount because they don't want to.
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Experiment studies
Experiment Design: My mom was considering buying an end of the year gift for my brothers football team. I thought buying gingerbread cookies would be a good idea. The gingerbread man cookies is the factor in our experiment. There are different options for designing the cookies, that all have different costs, and we were looking for the cheapest cookie idea. The treatments would be if I decided to get all the players numbers on the cookies or if I wanted to put everyones favorite colored sprinkles on their individual gingerbread. So we decided to get the football team gingerbread cookies with their numbers on it and my sisters cheerleading team gingerbread cookies with their favorite colored sprinkles on them to compare. In the end cookies with the different colored sprinkles were cheaper and where favored over the numbers. The response variable is the price of the cookie
Observational Studies
Lurking Variables
Defined: In an observational study lurking variables can cause confounding by changing the study and making it not accurate. Example: doing an experiment with number of people who need new computers and the lurking variable is number of people who dropped them and broke them
Difference
An observational study measures members of a sample without trying to affect them. While in an experiment the people/things being studied are assigned to groups and some groups are given treatment while some receive other or no treatment.
Examples Observational Studies: It was found that there was a delay with writing abilities in 1st graders and it was linked to mothers who drank during pregnancy. This would be an observation by seeing how children from mothers who drank and didn't drink during pregnancy's children preformed in the classroom.
Experiment: The bananas my dad bought last week started turning brown 5 days after he bought them but the bananas he bought a month ago didn't start turning brown till 10 days after. I think the temperature in my house those certain weeks were a factor. So I will buy two bunches of bananas and keep one of them in my basement, where it is the coldest, and one in the living room where it will reach the hottest temperature.
Survey:
When gathering information about whether dogs or cats are better animals I decided to use a simple random sample. Using any other sample could leave room for error or a biased sample.Using a random sample from Duxbury high school, I gave everyone a different number in the school and selected at random. Selecting at random consisted of me using any random line of numbers and picking the people that will give their vote from that.
