Research to provide evidence about whether a current or proposed program is needed.
A sample that has been selected without using a random sampling procedure. This type of sampling is less statistically rigorous because not every member of the population has an equal chance of being selected for the sample.
A source of non-sampling statistical error that occurs when some members of a sample refuse to become involved in the research. This means that the research becomes less representative of the sample
Statistical errors which occur due to factors other than how the sample for the research in drawn. These can include non-response, poor question design, poor quality interviewing and data capture and entry errors.
A theoretical distribution that 50 of observations will fall at either side of the (normal distribution) peak. Indicating that the value of the median is the same as the value of the mode.
Asserts that no relationship exists between two or more variables.