Week Two Flashcards
(10 cards)
What is standard deviation?
A measure of dispersion around the mean, it is also influenced by outliers.
Define measures of dispersion
The spread or distribution of values around some central value.
What are the sample parameters for a normal distribution?
68% + or - 1 SD from the mean
95% + or - 2SD from the mean
99.9% + or - 3SD from the mean
What is the Interquartile range?
Divides the observations into 4 groups.
What is variance?
The average squared deviation of each observation from the mean. The units are given in the squared units of the original measure.
What is the coefficient of variance (COV)?
It is used to compare dispersion of variables in different units, but cannot be calculated is the mean is 0.
The standard deviation divided by the mean x 100. It can only be used for ratio data and it unit less.
What is a non-random sample?
A sample collected without trying to avoid bias. They systematically overestimate or underestimate population parameters.
What are the issues with surveys?
Can the target population be established?
- coverage
- sampling
- non-response
- measurement
What the three measurement errors?
- Social desirability bias
- House effects
- Question wording/ order effect
What is the Likert scale?
This is an ordinal level of measurement, where respondents are given a range of options to chose from often in a scale. It is often treated as interval by assigning a score to each response.
