Topic 4 Flashcards
What is the measure of central tendency?
Summarises the data set with a SINGLE VALUE that is representative of the data set
e.g. mean, median, mode
Finish the scentence
If data is approximately normal, the mean, median, and mode will be ….
Equal
What is variability?
Extent to which things are not the same, how scores differ from one another
What is variability’s role in inferential statistics?
The amount of variability affects the kind of statements we can make about the population and the degree of confidence in these statements
What is variability’s role in descriptive statistics?
Variability is a property of the data
(descriptive stats) Does the mean better represent the data in a low variability or high variability data set?
Low
What is the range?
The largest score - the smallest score
How accurate is the range?
Not very accurate as it doesn’t take into account the distribution of the data
What is variance?
The sum of squared deviations from the mean divided by the number of scores
∑ (xi - x(bar) ) ^2 / n
What is the standard deviation?
Is approx the average distance of the scores from their mean
S = (Square root of). ∑(xi - x(bar) ) ^2 / n
Have to put n-1
What is an inflection point?
A point where the curve starts bending outwards more i.e not following a linear curve
How far away from the mean is an inflection point?
It is ALWAYS 1 standard deviation from the mean
What % of scores are within +/- 1 standard deviations of the mean?
68%
What % of scores are within +/- 2 standard deviations of the mean?
96%
What % of scores are within +/- 3 standard deviations of the mean?
99.7%
