Statistics for Social Research - Midterm 1

Field experiment

Takes place in an actual social setting, subjects may not know an experiment is taking place, researchers control randomization and assignment to treatment and control

Catergorical/Qualitative

Character/String

Nominal

Unordered lables

Ordinal

Ordered categories

Character

Unordered text

Factor

Ordered text categories

Numerical/Quantitative

Measurable data expressed in a number

Discrete

Can be counted

Continuous

Must be measured

Integer

Whole numbers

Numeric

Number with decimals

Right skew

Mean > median

Left skew

Mean < Median

Right skew examples

Anything with a natural bottom (often zero), but no ceiling

Natural experiment

Takes place in an actual social setting, manipulation is an actual change that affects a segment of the population while leaving the rest affected, treated and controls must be similar before

Lab experiment

Researchers simulate real world situations in a clinical space, validity depends on how convincing the manipulation is

Average treatment effects (ATE)

Sum of all observations divided by how many observations there are.

Counterfactual

Case of observing a variable under the conditions of the control and the treatment - often not possible

Data

Collection of information; observations and calculations

Variable

A characteristic that takes two or more possible values for some unit of observation

Constant

Something that takes only one value in a population or a sample

Qualitative

Consists of being in one category instead of another

Quantitative

Variation consists of having more or less of something

Population

Total set of subjects of interest in a study

Sample

Subset of the population on which the study collects data

Good sample

Representative, equal probability of being picked

Observational data

Non-experimental data

Histogram

Bar chart that shows the relative size of the categories

Distribution

Catalogue of all possible values a variable might take, noting the frequency of each value. List, count, plot

Mean

Arithmetic average

Positively skewed

More values above the average than below

Negatively skewed

More values below the average than above

Median

Center of the distribution

Range

Maximum - minimum

Interquartile Range

75th - 25th

Sum of squares

Way to measure spread, adds up (difference between values and the average)²

Box and whisker plot

Colored box with 25th to 75th percentile, whiskers to show ± 1.5 x IQR, outliers plotted as dots

Uniform distribution

Every outcome is more or less equally likely

Association

A pattern in which variation in one variable “goes with” variation in another variable

Scatterplots

Use when both variables quantitative

Histogram

Use when both variables qualitative

Line plot

Use when independent variable is qualitative and dependent variable is quantitative