Data collection Flashcards
What is population?
Sets of items that are of interest
What is census?
It measures every member of a population.
What is a sample?
A section of a population used to estimate a wider population.
What are the advantages of census?
It gives completely accurate results.
What are the disadvantages of census?
-Time consuming
-Can’t be used in a sampling system as it would destroy them
-Processing lots of data takes a long time
What are the advantages of sampling?
-Less time consuming
-Fewer responses needed
-Less data to process
What are the disadvantages of sampling?
-Data may not be accurate
-Sample may not properly represent population
What is simple random sampling?
Randomly picked so every element has an equal chance of being chosen.
What is systematic sampling?
Members are chosen at regular intervals from a list
What is stratified sampling?
Population is divided into groups
What is discrete data?
Data that can be only certain values (e.g only integers)
What is continuous data?
Data that can take any value, the only limitation is how accurately it can be measured
What are the advantages of systematic sampling?
-Simple and quick to use
-Suitable for large samples and large populations
What are the disadvantages of systematic sampling?
-Sampling frame needed
-It can be bias if sampling frame isn’t random
What are the advantages of stratified sampling?
-Sample accurately reflects population
-Guarantees proportional representation
What are the disadvantages of stratified sampling?
Population must be clearly classified into distinct data.
What are the advantages of simple random sampling?
-Free of bias
-Easy and cheap
-Each sampling unit has an equal chance of selection
What are the disadvantages of simple random sampling?
-Not suitable when population/sample size is large
-Sampling frame is needed
What are the 2 types of non-random sampling?
-Quota sampling
-Opportunity sampling
What is quota sampling?
Interviewer/researcher selects a sample that reflects the characteristics of the group.
What is opportunity sampling?
Group chosen from people available at the time who fit the criteria
What are the advantages of quota sampling?
-Quick and inexpensive
-Easy comparison between different groups in a population
-Even a small sample can represent population
What are the disadvantages of quota sampling?
-Can be bias
-Population can be divided into groups which can be costly/ inaccurate
When reading data in a table, what does n/a and tr mean?
n/a means no data available
tr means a number slightly bigger than 0 (e.g. 0.00001). When doing calculations refer to this as 0.
