POLI 380 Lecture Notes - Lecture 16: Categorical Variable, Sampling Bias
Document Summary
There are different types of variables: categorical, ordinal, continuous. Categorical variable: concepts and measures that place cases into discrete groups based on whether the characteristics are present or not, it could either be dichotomous or multichotomous. Placed in either two categories or various categories. Ordinal variable: types of multichotomous variables that have a natural order, for example, political ideology: very conservative, conservative, liberal or very liberal. Continuous variable: a measure involving continuous quantification of variation along a continuum, age, gdp growth, percentage of voters, there is always an equidistance in continuous measure. Sample is a subset of cases that are drawn from an underlying population. Population is every possible cases while sample is a smaller group drawn, sometimes at random, from the population. Samples are used to understand the population. Parameters could not vary but statistic could. Parameters covers the population while statistics measures the sample. There are also sampling error such as: sampling bias, random sampling error.
