Stats 1 Flashcards
Define population
A complete set of data where every element is included
Define sample
A selection of the population
Define census, why is it rare?
Every element is surveyed, rare because it is expensive and labor-intensive
Define sampling units
These are the elements of data in a sample
Define sampling frame
A list of sampling units
Define random sampling methods
Every element of the population has an equal chance of being selected
What are the 3 random sampling methods?
Simple random sample, systematic sample and stratified sampling
Define simple random sample
Using random numbers or ‘names out of a hat’
Define systematic sample
All elements numbered, the first element is chosen randomly then every nth element is chosen
Define stratified sampling
The proportion of groups in the population are represented in the survey
What is the danger of non-random sampling?
Bias
Define opportunity sampling
Your sample is whoever turns up
Define quota sampling
Numbers are calculated for each group then when groups are filled, others are ignored
Define qualitative data with examples
Groups of data, non-numerical, qualities like colours
Define quantitative data with examples
Numerical data, quantities like temperature
What two types of data can quantitative data be sectioned into?
Discrete and continuous
What is discrete data?
Whole numbers, can’t be decimals, like when you’re counting something
What is continuous data?
Data that can take any value, including decimals, for example, height, it can continue between each whole number of kilograms
What does n/a mean?
Not available, used when the data needed is not available
If one cell of data has n/a in it, what should you do to the whole row?
Ignore it
What does tr mean?
Trace, there was some but not enough to provide a reading and more than 0
If a cell of data has tr in it, what should you do to it? Why?
Change it to 0 so it can be included in means and other calculations
How is daily mean temperature measured?
Values are noted in degrees (Celsius) and tenths, values below 0 are preceded by a minus sign
What is the daily mean temperature?
The average of the hourly air temperature readings during the period 0900-0900 GMT