1.5 the sources of bias in sampling

bias

when the results of a sample are not representative of the population

non response bias

occurs when individuals selected to be in the sample do not respond, do not wish to respond or are unable to be reached

response bias

exists when the answers on the survey do not reflect the respondents true feelings

sampling bias

occurs when there is under coverage

undersampling

the portion of one segment of the population is lower in the sample than it is in the population

sampling error

results from using a sample to estimate information about a population

non sampling error

nonresponse and response error, data entry errors and under coverage