2 constant versus variables

Constant

Characteristic that does not change within the context of a study. It remains fixed for all individuals under observation.

Constants

help define the scope and limits of a study, but they are not subjected to statistical analysis since they do not provide variation.

Variable

Any characteristic or attribute that can take on different values among individuals or over time.

Variables

are the focus of statistical analysis since they provide the information necessary to identify patterns, relationships, and differences within a population.

constant

a _____ does not change within the scope of the study; it is fixed for all participants

variable

a _____ changes from person to person or over time; it is the focus of the statistical analysis

Data

raw facts collected in a study

Qualitative (Categorical) Data

describe categories or qualities rather than numbers.

Nominal Data

represent categories without any inherent order.

are used for labeling and grouping only

Ordinal Data

Data that represent categories with a logical order, but the differences between categories are not uniform

Quantitative (Numerical) Data

involve numbers that reflect measurable quantities.

Discrete Data

Data that can only take whole number values and are usually the result of counting.

Continuous Data

Data that can take any value within a range and are usually obtained by measuring.

expressed in fractions or decimals.

Primary Data

These are data collected firsthand by the researcher for a specific study.

Survey responses, laboratory results from a clinical trial, or measurements gathered directly by the investigator.

Primary data

usually more reliable and tailored to the research objectives but may be costly and time-consuming to obtain.

Secondary Data

These are data collected by other researchers or institutions but used for a new analysis.

Hospital records, government health statistics, census reports, and previously published studies.

Secondary data

easier to obtain and less costly, but the researcher must ensure their accuracy and relevance to the current research question.

Experimental Data

These are collected from controlled experiments in which the researcher manipulates one or more variables to observe their effect on other variables.

In a randomized clinical trial, a group of patients may receive a new drug while another group receives a placebo, and the outcomes are compared.

Experimental data

powerful for establishing cause-and-effect relationships

Observational Data

These are obtained without any intervention from the researcher. Instead, the investigator records data as they naturally occur.

Cross-sectional surveys, cohort studies, and case-control studies.

Observational data

common in public health and epidemiology, especially when experiments are not feasible due to ethical or practical concerns.

primary data is data - specifically for the study

firsthand by the researcher

secondary data is data collected by -, but used for a new study

other researchers or institutions

experimental data is data obtained from -, where variables are manipulated to observe outcomes

controlled experiments

observational data is data obtained by -, without manipulating variables

observing subjects naturally