Module 1 Flashcards
What are sampling errors?
Errors that occur when the analyst selects a sample that is not representative of the population being studied. Sampling errors become less important as the sample size increases.
What are systematic errors?
A consistent, repeatable error associated with faulty equipment or a flawed experimental design (eg incorrectly calibrated equipment). Such errors do not necessarily decrease as the sample size increases.
What is descriptive statistics?
Any summary describing each variable, such as the mean age of the group or the proportion of males. It also includes measures of association between variables, such as mean differences, risk differences, risk ratios, odds ratios, correlations, etc.
What is statistic inference?
The statistical methods used to generalise the sample results to the population, such as confidence intervals and hypothesis tests.
What is a quantitative variable?
A variable that can be counted or measured.
What is a variable?
An item of data that can be observed or measured on individuals.
What is a discrete variable?
A quantitative variable whose possible values are integers (whole numbers), eg number of children, number of visits to a GP in a year.
What is a continuous variable?
A quantitative variable that has an uninterrupted range of values, eg BP, weight.
What is a categorical variable (qualitative variable)?
A variable that is not characterised by a numerical quantity, eg sex, occupation, type of housing, diet quality, disease category.
What is an ordinal variable?
A qualitative variable with several categories which have an order, eg diet quality may be very poor, poor, fair, or good.
What is a nominal variable?
A qualitative variable with categories that have no natural order, eg disease category may be heart disease, cancer, respiratory disease, other.
What is a dichotomous variable (or binary or dummy variable)?
A qualitative variable with just two classes, eg yes/no, dead/alive, symptom present/absent. Dichotomous variables can be seen as a special case of a nominal variable.
What is a statistic?
A numerical value describing a characteristic of a sample, eg frequency, relative frequency (or percentage).
What is a parameter?
A measure that describes a characteristic of a population (rather than sample), eg population mean age.
What are measures of central tendency?
For a quantitative variable, a single figure that indicates the general magnitude of a series of measurements, eg mean, median and mode
