# Preliminaries and Descriptive Statistics Flashcards

What is a variable?

Something that can vary

What are the three types of variable?

- Categorical: non-numerical
- Continuous: numerical but doesn’t have to be a whole number
- Discrete: numerical and a whole number

What does a population consist of?

people or items that share a particular characteristic (or set of characteristics)

What does a sample refer to?

to a selection of individual people or items from a population

In statistics what are we trying to do in regard to populations and samples?

draw inferences about a population from a sample

What is a population parameter?

a quantity that describes some characteristics of a population with respect to a specific variable (needs to be worked out with the entire population)

What is a sample statistic?

A quantity that describes some characteristic of a sample with respect to a specific variable

Why is it usually hard to calculate population parameters?

We don’t have access to the entire group

Why is it important to summarise data?

It can be very complex and there can be lots of it

What should a measure of central tendency provide?

An indication of a ‘typical’ score in the data set

What are the three measures of central tendency?

- Mean
- Median
- Mode

How do you work out the mean?

Add all scores together and divide by number of scores (N)

What are the pros and cons of using the mean?

- Pro: provides an estimate of the average score of the data-set
- Con: is affected by extreme data points

What is the mean?

The average

What is the median?

Value that lies in the middle of the data