Created by Culan O'Meara
about 9 years ago


Question  Answer 
Mean  Mean is a measure of central tendency. Sum of numbers/total number of numbers 
Mode  Mode is a measure of central tendency. Most common number 
Median  Median is a measure of central tendency. Middle number 
Central Tendency  Gives an indication of the "middle" of a set of data. it is measured using the mean, median and mode. Each of these is calculated differently and the one that is best to use depends on the data you have 
Range  Range = Largest  smallest 
Interquartile range  Upper quartile  lower quartile. 
Shape of distribution  Shape refers to whether a data is normally distributed, skewed left/negatively or skewed right/positively 
Outlier  A value that "lies outside" (is much smaller or larger than) most of the other values in a set of data. For example in the scores 25,29,3,32,85,33,27,28 both 3 and 85 are "outliers". 
Primary v Secondary Data  Primary data is data you collect yourself through survey/experiment/investigation. Secondary data is data you find through a newspaper/website/etc. Basically data that someone else has collected 
Categorical v Numerical  Categorical data is nonnumerical data and can be ordered or nominal Numerical data has numbers and can be discrete or continuous 
Bias  Bias occurs when the survey sample does not accurately represent the population. The bias that results from an unrepresentative sample is called selection bias 
Simple Random Sample  Random sampling is a procedure for sampling from a population in which: (a) the selection of a sample unit is based on chance (b) every element of the population has an equal chance of being selected. 
Representativeness  It is the closeness of the sample to the population from which the sample has been taken 
Population  A population is any entire collection of people, animals, plants or things from which we may collect data. It is the entire group we are interested in, which we wish to describe or draw conclusions about. 
Sample  A sample is a group of units selected from a larger group (the population). 
Parameter  A parameter is a value, usually unknown (and which therefore has to be estimated), used to represent a certain population characteristic 
Statistic  A statistic is a quantity that is calculated from a sample of data. 
Census  Collection of data from a whole population rather than just a sample 
Sampling Variability  Difference (or variance) between sample statistics from different samples. Example: If I ask 10 people their height and find the mean height of those, it may well be different to the mean height of another 10 people I ask. This difference is sampling variability 
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