data sources such as population lists, directories, or maps
Inaccurate or biased results can result if
a frame excludes certain portions of the population
items are selected based only on the fact that they are easy, inexpensive, or convenient to sample
you get the opinions of pre-selected experts in the subject matter
items included are chosen without regard to their probability of occurrence.
items in the sample are chosen on the basis of known probabilities
Simple random sample and Systematic sample
1. Simple to use 2. May not be a good representation of the population's underlying characteristics
Ensures representation of individuals across the entire population
1. More cost effective 2. Less efficient (need larger sample to acquire the same level of precision)
Coverage error or selection bias
Exists if some groups are excluded from the frame and have no chance of being selected
Non response error or bias
People who do not respond may be different from those who do respond
Variation from sample to sample will always exist
Due to weaknesses in question design, respondent error, and interviewer's effects on the respondent
is a distribution of all of the possible values of a sample statistic for a given size sample selected from a population
Different samples of the same size from the same population will yield
different sample means
Standard Error of the Mean
A measure of the variability in the mean from sample to sample
standard error of the mean decreases
as the sample size increases
As the sample size gets large enough...(Central Limit Theorem)
the sampling distribution becomes almost normal regardless of shape of population
True or False: Sampling error becomes an ethical issue if the findings are purposely presented without reference to sample size and margin of error so that the sponsor can promote a viewpoint that might otherwise be truly insignificant.
For sample size 16, the sampling distribution of the mean will be approximately normally distributed
if the shape of the population is symmetrical.
True or False: A sample is selected by including everybody who sits in the first row of a business statistics class. This is an example of a cluster sample.
For sample size 1, the sampling distribution of the mean will be normally distributed
only if the population is normally distributed.
True or False: Systematic samples are less efficient than stratified sample.
types of samples can you use if you want to make valid statistical inferences from a sample to a population?
A probability sample
True or False: A sample is always a good representation of the target population.
True or False: Chunk sample is a type of probability sample.
True or False: The question "How many times have you abused your spouse in the last 6 months?" will most likely result in nonresponse error.
True or False: As a population becomes large, it is usually better to obtain statistical information from the entire population.
True or False: The question: "How much did you make last year rounded to the nearest hundreds of dollars?" will most likely result in measurement error.
True or False: The only way one can eliminate sampling error is to take the whole population as the sample.
True or False: The only reliable way a researcher can make statistical inferences from a sample to a population is to use nonprobability sampling methods.