Exam Revision Flashcards
Statistics
Statistics is the branch of mathematics that examines ways to process and analyse data. Statistics provides procedures to collect and transform data in ways that are useful to business decision makers. To understand anything about statistics, you first need to understand the meaning of a variable.
4 fundamental terms of statistics
Population
Sample
Parameter
Statistic
Population
A population consists of all the members of a group about which you want to
draw a conclusion.
Sample
A sample is the portion of the population selected for analysis
Parmeter
A parameter is a numerical measure that describes a characteristic of a
population (measures used to describe a population) GREEK LETTERS REFER
TO A PARAMETER
Statistic
A statistic is a numerical measure that describes a characteristic of a sample
(measures calculated from sample data) ROMAN LETTERS REFER TO
STATISTICS
2 types of statistics
Descriptive statistics
Inferential statistics
Descriptive statistics
Collecting, summarising and presenting data
Inferential statistics
Drawing conclusions about a population based on sample data/results (i.e. estimating a parameter based on a statistic such as hypothesis testing.
2 types of data
Categorical (defined categories)
Numerical (quantitative)
2 types of numerical variables
Discrete (counted items)
Continuous (measured characteristics)
4 levels of Measurement and Measurement Scales from highest to lowest
Ratio data
Interval data
Ordinal data
Nominal data
Ratio data
Differences between measurements are meaningful and a true zero
exists
Interval data
Differences between measurements are meaningful but no true zero
exists (has negatives)
Ordinal data
Ordered categories (rankings, order or scaling)
Nominal data
Categories (no ordering or direction)
4 measures used to describe data
Central tendency
Quartiles
Variation
Shape
4 measures of central tendency
Arithmetic mean
Median
Mode
Geometric mean
5 measures of variation
Range Interquartile range Variance Standard deviation Coefficient of variation
1 measure of shape
Skewness
Arithmetic mean
Arithmetic mean is summing up the observations and dividing by the number of observations.
Median and mode extreme values
The median is not sensitive to extreme values and the mean is sensitive to extreme values.
Sigma
Sigma is short for adding up the values
Median
In an ordered array, the median is the middle number (50% above and 50%below). It’s main advantage over the arithmetic mean is that it is not affected by extreme values.