Statistical Methods- Lecture 1-2 Flashcards
What are the 2 defining characteristics of a variable?
1) A variable is an attribute that describes a person, place, thing, or idea.
2) The value of the variable can ‘vary’ from one entity to another.
What are the different types of variables?
All variables are made up of either numerical or categorical.
Numerical can be either continuous or discrete.
Categorical can be either nominal or ordinal.
What type of variable is a telephone area code?
Categorical, nominal
What are associated variables?
When two variables show some connection with one another, they are called associated variables. Associated variables are also known as dependent variables.
What are independent variables?
If two variables are not associated, then they are said to be independent.
What is the explanatory variable?
It’s value ‘explains’ variations in the response variable. Also know as the independent variable. It is usually plotted on the x-axis.
What is the response variable?
It’s value is ‘predicted’ or its variation is ‘explained’ by the explanatory variable. Also known as the dependent variable. Usually plotted on the y-axis.
What is a census?
A census is where you sample the entire population. It can be difficult to do this as there are always individuals who are hard to locate or measure and may have characteristics that distinguish them from the rest of the population.
What is the sampling bias for non response?
If only a small fraction of the randomly sampled people choose to respond to a survey, the sample may no longer be representative of the population.
What is the sampling bias for voluntary bias?
Occurs when the sample consists of people who volunteer to respond because they have strong opinions on the issue. They would not represent the whole population.
What is the sampling bias for convenience sample?
Individuals who are easily accessible are more likely to be included in the sample
What is the sampling bias for subjective subject?
Individuals are chosen using the subjective judgement of the researcher, e.g. who they believe are representative of the population
What are observational studies?
Researchers collect data in a way that does not directly interfere with how the data arises. This can be used to establish an association between variables.
What are experimental studies?
Researchers collect data by introducing interventions and observing the effects. This can be used to establish causation between variables
What are prospective and retrospective studies?
A prospective study identifies individuals and collects information as events unfold. Meanwhile, retrospective studies collect data after events have taken place.
