question

population

answer

all of the people of interest in a study

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sample

answer

some of the individuals of interest

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sample survey

answer

some of the individuals of interest are surveyed to get information about all of the individuals, aka the population

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census

answer

an attempt to survey all of the population

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random sampling error

answer

the error that occurs when we estimate a population characteristic by looking at only one portion of the population rather than the entire population

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confidence interval quick method

answer

Adding and subtracting the margin of error to the sample proportion

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margin of error formula

answer

1/square root of n, n = whole of sample

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statistic vs. parameter

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Statistic: the percentage of the sample
Parameter: percentage of the population

question

True or False: When we take a census we try to get information from every member of a simple random sample.

answer

False - with a census we try to get information from every member of a whole population.

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True or false: Nonsampling errors could occur, even if we take a census.

answer

True - nonsampling errors have to do with study methods and bias, which can occur regardless of the sample.

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True or false? Margin of error only covers random sampling error.

answer

True - margin of error does not account for nonsampling errors.

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True or false? Margin of error covers the effects of bias in the sampling method.

answer

False - margin of error only covers random sampling errors, not bias.

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2 examples of sampling errors

answer

Random sampling error, undercoverage

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3 examples of nonsampling errors

answer

Nonresponse, response (wrong) error, question wording, data entry error

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How do you improve a biased sampling method?

answer

Take a random sample of the population of interest, take a larger sample - do not use the same sampling method.

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How do we improve sampling method that yields too much variation in the resulting statistics?

answer

Take a larger sample.

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Simple random sample vs stratified sample?

answer

Simple random means all members of a population have an equal chance of being selected.
Stratified divides the population into distinct groups (girls vs boys) and then takes random samples from there.

question

Bias
Reliability
Validity

answer

Bias - consistently measures +/- a number,
Reliability - does not consistently measure
Validity - whether it actually measures what it purports to measure

question

What are the possible values of standard deviation?

answer

0, or any positive number.

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When data is symmetric, which summary statistics are used?

answer

Mean and standard deviation to report center and spread of the data.

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When data is skewed, what summary statistics are used?

answer

Five number summary

question

z-score formula

answer

Z=(observation - mean)/standard deviation