Statistics 1.4

Bias

if the results of the sample are not representative of population then the sample has bias

Bias

The technique used to obtain the individuals in the sample tends to favor one part of the population over another.

Voluntary response data or self-selected sample

Respondents themselves decide whether to be included.

Nonresponse bias

Individuals selected to be in the sample who do not respond to the survey have different opinions from those who do

Response bias

The answers on a survey do not reflect the true feelings of the respondent. Misleading Conclusion

Nonsampling error

the result of human error, including such factors as wrong data en tries, computing errors, questions with biased wording, false data provided by respondents, forming biased conclusions, or applying statistical methods that are not appropriate for the circumstances. (Includes undercoverage, nonresponse bias and response bias

Sampling error (or random sample error)

occurs when the sample has been selected with a random method, but there is a discrepancy between a sample result and the true population result.

Nonrandom sampling error:

result of using a sampling method that is not random, such as using a convenience sample or a voluntary response

Placebo:

harmless & ineffective pill, medicine, or treatment sometimes used for psychological benefit or sometimes used by researchers for comparison to other treatments

Experimental Units:

The individuals or items on which the experiment is performed. When the experimental units are people, we call them subjects