1.1 - The Practice of Political Scientists
Political scientists build their understanding of political systems by systematically studying evidence. They look at political behavior, institutions, and interactions in order to explain how politics works and to make inferences from what they observe.
Types of Data They Use
Political scientists pull from a wide range of sources to compare countries and draw conclusions, including:
- Charts, tables, and graphs (numerical data)
- Speeches (political rhetoric and messaging)
- Foundational documents like constitutions and laws
- Political cartoons (satire on current events)
- Maps (geographic and demographic info)
- Political commentary (expert analysis and opinion)
They also rely heavily on quantitative methods, meaning empirical data and statistics, to compare countries systematically, spot patterns, measure relationships, and test hypotheses.
These sources come in two kinds. Quantitative sources are numbers: charts, tables, graphs, and maps that show data. Qualitative sources are text or images: speeches, foundational documents, political cartoons, and political commentaries. For a quantitative source, describe what the data shows, then look for patterns and trends. For a qualitative source, find the author's claim, the evidence behind it, and the author's perspective. Both let political scientists make comparisons between course countries and inferences (conclusions that go beyond what the source says directly).
Causation vs. Correlation
Figuring out causation in comparative politics is genuinely hard. Political outcomes come from a ton of variables happening at once, so it's tough to isolate exactly what caused a specific change. For example, if a country's economy improves after an election, is that because of the new leadership, because old policies are finally kicking in, because of global economic trends, or some mix of all three?
Correlation just means two or more variables move together, there's an association. But correlation doesn't prove causation. Both variables might be driven by some third factor, or the relationship might just be coincidence.
A correlation can be positive (both variables rise together) or negative (one rises while the other falls). For example, countries with higher Freedom House scores usually have higher Corruption Perceptions Index scores (meaning less corruption), so the two are positively correlated. That still doesn't prove democracy causes cleaner government: richer countries tend to score well on both, so wealth could be the third factor. China also breaks the pattern, scoring 9 out of 100 on Freedom House but 43 on the Corruption Perceptions Index, higher than Mexico (27) or Nigeria (26).
Empirical vs. Normative Statements
There's an important distinction researchers have to keep straight:
- Empirical statements are factual and objective, they can be checked against evidence and proven true or false. Example: "Voter turnout in Country X dropped 12% in the last election."
- Normative statements are value judgments about what should happen or what's desirable. Example: "Low voter turnout is bad for democracy."
Political scientists build their knowledge on empirical statements, even though they sometimes touch on normative questions in their research.
The Comparative Method
This is exactly what it sounds like: looking at different political systems side by side to draw conclusions. By comparing how different countries deal with similar problems, or how similar institutions function in different settings, researchers can figure out which factors actually matter most.
Data Collection Resources
There are several standardized indices political scientists use to study relationships between countries:
- Human Development Index (HDI): combines life expectancy, education, and standard of living into one measure
- Published every year by the UN Development Programme (UNDP). Scores run from 0 to 1, and higher is better. It measures three things: a long and healthy life (life expectancy at birth), knowledge (expected and average years of schooling), and a decent standard of living (gross national income per capita).
- Gross Domestic Product (GDP): total value of goods and services produced; GDP per capita adjusts for population
- GDP shows the size of an economy, while GDP per capita (GDP divided by population) is better for comparing how well off people are. China has the world's second-largest GDP, but its GDP per capita is far below the UK's because China has about 20 times as many people.
- GDP Growth Rate: percentage change in economic output over time
- Gini Index/Coefficient: measures income inequality (0 is perfect equality, 100 is perfect inequality)
- As a coefficient it runs from 0 to 1, and as an index from 0 to 100. Either way, higher means more unequal. It measures how evenly income is spread, not how rich a country is, so a poor country can have a lower Gini than a rich one.
- Freedom House: rates political rights and civil liberties around the world
- A US-based nonprofit. Its yearly Freedom in the World report scores political rights (0 to 40) and civil liberties (0 to 60) for a total out of 100, then labels each country Free, Partly Free, or Not Free. It's the go-to measure for placing a regime on the democracy vs. authoritarianism spectrum (Topic 1.3).
- Transparency International: tracks how corrupt countries are perceived to be
- Its main tool is the Corruption Perceptions Index (CPI), which scores countries from 0 (highly corrupt) to 100 (very clean) based on how experts and business people see public-sector corruption. It measures perceptions because most corruption is hidden and can't be counted directly.
- Failed States Index: measures how fragile a state is and its risk of collapse
- Published by the Fund for Peace, it was renamed the Fragile States Index in 2014. It scores 12 indicators (such as security, group grievances, economic decline, public services, and state legitimacy) from 0 to 10 each, for a total out of 120. A higher score means a more fragile state.
These tools give political scientists the empirical data they need to apply concepts, support generalizations, and build arguments about political systems.
Course Countries by the Numbers (as of 2026)
Here's where the six course countries stand on three of these measures. The exam always gives you the data, so you don't need to memorize these numbers, but knowing the general picture makes data questions much easier.
Country | Freedom House 2026 (out of 100) | Corruption Perceptions Index 2025 (0 to 100) | HDI (2023 data, 0 to 1) |
United Kingdom | Free (92) | 70 | 0.946 |
Mexico | Partly Free (58) | 27 | 0.789 |
Nigeria | Partly Free (44) | 26 | 0.560 |
Russia | Not Free (12) | 22 | 0.832 |
Iran | Not Free (10) | 23 | 0.799 |
China | Not Free (9) | 43 | 0.797 |
A few patterns to notice: the UK leads on all three measures. Russia, Iran, and China are all rated Not Free, yet their HDI scores are higher than Mexico's, so human development and democracy don't always go together. Nigeria has by far the lowest HDI of the six (life expectancy there is about 54 years). Sources: Freedom House, Freedom in the World 2026; Transparency International, CPI 2025; UNDP, Human Development Report 2025 (2023 data).
How to handle a data question on the exam:
- Read the title, labels, units, years, and source before anything else.
- Describe the data accurately, using specific numbers ("Nigeria's HDI is 0.560, the lowest of the six").
- Identify the pattern or trend: what's rising or falling, what's highest or lowest, where the big gaps are.
- Draw a conclusion: explain what the pattern shows about a political concept, like legitimacy, democratization, or corruption.
- Know the limits: data can show a correlation but not prove causation, and some indices (like the CPI) measure perceptions.