Chapter 4: Descriptive Measures Of Location Flashcards
What is a statistic
Statistic is a value determined from a sample which is used to summarise the information contained in a data set
What is a parameter
A summarising value determined from the population
What is a measure of location
A measure of location attempts to determine by a single number the centre/position of the population or the sample of interest
Name the four basic measures of location
Arithmetic mean
Mode
Median
Quantile
What is the sensible assumption
The assumption usually made is that all the observations in a class are situated in the centre of the class i.e. at the midpoint
It is not always true
What are outliers
Outliers are values in a data set that is either extremely large or extremely small relative to the other observations in the data set
What is the mode
A value with the highest frequency i.e. the value that occurs most frequently
What are the properties of mode
The mode is not influence by outliers
The mode does not possess the relative mathematical properties associated with the arithmetic mean
The mode is not always uniquely defined i.e. it is possible to have more than one mode per dataset
Most successful when applied to discrete data
What is the median
The median is the number that is situated in the centre of the observations if the observations are arranged from smallest to largest
What is a quartile
Quartiles are those values that divide an ordered data set into four equal parts
A positively skewed distribution is skewed to what direction
The right
A negatively skewed distribution is skewed to what direction
The left
In what distribution is the mean typically larger than the median and the mode
Positively skewed distribution
What are the properties of arithmetic mean
In the calculation of arithmetic mean all the observations are used. Because of this it has mathematical properties.
It is unique for each specific data ser
Its is vulnerable to outliers
What are the properties of the median
It is not influenced by outliers
Similar to the mode it does not posses relative mathematical properties
