Flashcards in Statistics Deck (23)
What are qualitative variables?
Have non-numerical observations
What is continuous data?
Measured on a scale and can take any value on that scale
What is Discrete data?
In most cases data concerned with a number of countable values
What is categorical data?
Data which have a scale grouped in different categories
What is ranking data?
Is ordered categories of data eg. Year groups in schools
What is bivariate data?
When every observation has two pieces of data (scatter graphs)
Collected by or for the person who is going to use it
~you know who and how it was collected
~you know accuracy and reliability
~limited to collecting from certain people
Not collected by or for the person who will use it
~easy to find
~larger sample than you can get yourself
~more representative of all people
~don't know how it was collected so isn't fully reliable
~may be out of date
~might not quite fit with your purpose
What is a statistical experiment?
An experiment where one of the variables will always be controlled engle its affect on the other variable is observed
What does respondent mean?
It is what you call a person who has completed a questionnaire
How do you generate random numbers on a calculator?
For example between 1 and 32
What is a random sample?
Each item of the population has an equal chance of being selected
What is stratified sampling?
When you divide the population into categories/strata (by age, gender, social class ect.) and within these groups take a random sample proportional to the relative size from which the stratum is taken
What is systematic sampling?
A sample which is obtained by choosing at regular intervals from an ordered list
What is cluster sampling?
The population which is being tested is split into clusters then a cluster is randomly chosen and every item is looked at
What is quota sampling?
Instructions are given (by the surveyor) about the amount of each section of the population with a certain characteristic
What is Convenience sampling?
Choosing the first names on a list
What are pie charts?
They show proportions for each category (not frequencies) from the fraction of the circle
What is the formula for the histogram frequency density?
Frequency density=frequency / class width
Frequency=frequency density x class width
What is the formula for Index numbers?
Index number= quantity / quantity in base year x 100
Simple index numbers:
Price relative=price/price in base year x100
What is an outlier?
An outlier is any value which is 1.5 (or more) times the inter quartile range below or above the interquartilerange
What is t PhD formula for standardised scores?
Standardised score= score-mean /