Data basics

Question 1

Case or Observational Unit

Answer 1

Each row in a dataset represents a single instance or entity being studied, called a case or observational unit. For example, in a loan table, each row represents a single loan.

Question 2

Variables

Answer 2

Characteristics or attributes of each case or observational unit, represented as columns in a dataset. For instance, in a loan table, variables include loan amount, interest rate, borrower location, and income.

Question 3

Data Matrix

Answer 3

A structured way to organize data, often used in spreadsheets, where each row corresponds to a unique case (observational unit) and each column corresponds to a variable.

Question 4

Numerical

Answer 4

A variable that can take a wide range of numerical values and allows meaningful mathematical operations such as addition, subtraction, or averaging. For example, unemployment rate or population count.

Question 5

Discrete

Answer 5

A type of numerical variable that can only take whole numbers or values with jumps, such as population count (0, 1, 2, …).

Question 6

Continuous

Answer 6

A type of numerical variable that can take any value within a range, allowing for decimals and fractions, such as the unemployment rate.

Question 7

Categorical

Answer 7

A variable where responses fall into distinct categories or groups. For example, the variable “state” with values such as AL, AK, or WY.

Question 8

Level

Answer 8

The possible values a categorical variable can take. For instance, the variable “state” has levels like AL, AK, WY, etc.

Question 9

Ordinal

Answer 9

A categorical variable with levels that have a natural ordering. For example, median education level (below HS, HS diploma, some college, bachelor’s).

Question 10

Nominal

Answer 10

A categorical variable with levels that do not have any inherent order. For example, telephone area codes or state names.

Question 11

Explanatory Variable

Answer 11

A variable that is believed to influence or explain changes in another variable. For example, median household income in a study examining its effect on population change.

Question 12

Response Variable

Answer 12

A variable that is affected or influenced by the explanatory variable. For example, population change in a study investigating the impact of median household income.

Question 13

Observational Study

Answer 13

A study where researchers collect data without interfering with how the data arise, such as through surveys, reviewing records, or tracking a cohort. It can show associations but not causation.

Question 14

Cohort

Answer 14

A group of similar individuals followed over time in a study, often to observe the development of certain outcomes, such as diseases.

Question 15

Experiment

Answer 15

A study where researchers actively intervene to investigate a possible causal connection by assigning treatments to study participants and observing outcomes.

Question 16

Randomized Experiment

Answer 16

An experiment where participants are randomly assigned to treatment groups, ensuring unbiased distribution of characteristics across groups.

Question 17

Placebo

Answer 17

A fake treatment used in experiments to control for the psychological effects of receiving a treatment, helping to isolate the true effects of the actual treatment.

Question 18

Data

Answer 18

Observations collected from sources such as field notes, surveys, and experiments, forming the foundation of a statistical investigation.

Question 19

Statistic

Answer 19

The study of how to best collect, analyze, and draw conclusions from data.

Question 20

Sample

Answer 20

A subset of the population, often a small fraction, used to represent and draw conclusions about the whole population.