College Political Science Quiz: Evaluating Causation
20 questions · exam conditions
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Evaluating CausationQuestion 1 of 20

A scholar finds that a study correlating education levels with income suffers from endogeneity because unobserved ambition might affect both. To address this, the scholar uses a student's month of birth as an instrumental variable, arguing that school entry-age policies cause students born late in the year to have slightly less schooling than those born early in the year. For this instrumental variable to be valid, which of the following must be true?

Month of birth must be strongly correlated with future income but uncorrelated with actual years of schooling.
Month of birth must be a perfect predictor of an individual's ambition and their final education level.
Month of birth must be correlated with years of schooling but have no direct effect on income other than through its effect on schooling.
Month of birth must be shown to be statistically independent of all other variables that could possibly affect income.
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College Political Science Quiz

College Political Science Quiz: Evaluating Causation

Practice Evaluating Causation in College Political Science with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Evaluating Causation, giving you a quick way to practice the rules, question types, and explanations that matter most for College Political Science.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

A scholar finds that a study correlating education levels with income suffers from endogeneity because unobserved ambition might affect both. To address this, the scholar uses a student's month of birth as an instrumental variable, arguing that school entry-age policies cause students born late in the year to have slightly less schooling than those born early in the year. For this instrumental variable to be valid, which of the following must be true?

  1. Month of birth must be strongly correlated with future income but uncorrelated with actual years of schooling.
  2. Month of birth must be a perfect predictor of an individual's ambition and their final education level.
  3. Month of birth must be correlated with years of schooling but have no direct effect on income other than through its effect on schooling. (correct answer)
  4. Month of birth must be shown to be statistically independent of all other variables that could possibly affect income.
Explanation: A valid instrumental variable must satisfy two core assumptions: 1) The 'relevance' assumption: the instrument (month of birth) must be correlated with the endogenous independent variable (education). 2) The 'exclusion restriction': the instrument must affect the dependent variable (income) only through the independent variable. In other words, month of birth cannot have a direct impact on income for any reason other than its effect on education. Choice (C) correctly states these two conditions.

Question 2

A scholarship program is awarded to all high school students with a grade point average (GPA) of 3.50 or higher. A researcher compares the college completion rates of students with a 3.51 GPA (who received the scholarship) to students with a 3.49 GPA (who did not). This regression discontinuity design is a powerful tool for causal inference primarily because it assumes that:

  1. students just above and just below the arbitrary cutoff are, on average, nearly identical in all other relevant characteristics. (correct answer)
  2. the GPA cutoff of 3.50 was chosen randomly by the program administrators.
  3. all students who receive the scholarship will successfully complete college due to the financial assistance.
  4. GPA is the single most important predictor of college success, rendering other factors insignificant.
Explanation: Regression discontinuity design (RDD) is a powerful quasi-experimental method that exploits arbitrary cutoffs to estimate causal effects. When you see RDD questions, focus on the key assumption that makes this design work for causal inference. The strength of RDD lies in the assumption that individuals just above and below an arbitrary threshold are essentially identical except for their treatment status. In this scholarship example, students with a 3.51 GPA versus 3.49 GPA are likely very similar in motivation, ability, family background, and other characteristics that affect college completion. The tiny GPA difference is often due to random factors rather than systematic differences. This creates a "natural experiment" where treatment assignment (scholarship eligibility) is virtually random near the cutoff, allowing researchers to isolate the causal effect of the scholarship. Option A correctly identifies this core assumption - that students near the cutoff are nearly identical in all relevant characteristics except scholarship receipt. Option B is wrong because the cutoff doesn't need to be randomly chosen; it just needs to create similar groups on either side. Option C makes an unrealistic assumption about guaranteed success - RDD doesn't assume universal treatment effects. Option D incorrectly suggests other factors don't matter, when RDD actually controls for these factors through the similarity assumption near the cutoff. Remember: RDD's power comes from comparing very similar individuals who happen to fall on opposite sides of an arbitrary line. Look for this "local randomization" concept whenever you encounter regression discontinuity questions.

Question 3

A study of 25 post-communist Eastern European nations finds that the implementation of market liberalization policies in the 1990s is causally associated with higher GDP growth. The authors suggest this finding provides strong evidence for the universal benefits of market liberalization. What is the most significant limitation regarding the scope conditions of this causal claim?

  1. The causal relationship may be reversed, as higher GDP growth could have enabled further market liberalization.
  2. The study fails to account for the role of international aid, which is a confounding variable that also affects GDP growth.
  3. There is likely measurement error in GDP figures from the 1990s, making the quantitative results unreliable.
  4. The study's findings are specific to a unique historical context and may not be generalizable to countries without a legacy of state socialism. (correct answer)
Explanation: When evaluating causal claims in political science research, you need to distinguish between different types of validity threats. This question tests your understanding of external validity—specifically, scope conditions that limit how broadly research findings can be generalized. The correct answer is D because the study examines a very specific set of countries (post-communist Eastern European nations) during a unique historical transition (the 1990s shift from state socialism to market economies). These countries shared distinctive characteristics: existing industrial infrastructure, educated populations, relatively developed institutions, and the particular challenges of transitioning from centrally planned economies. The authors' claim about "universal benefits" of market liberalization ignores these unique scope conditions. The causal relationship observed in this specific context may not apply to countries with different starting points, such as developing nations without industrial bases or countries that never experienced state socialism. Option A describes reverse causality, which is about causal direction rather than scope conditions. Option B identifies a potential confounding variable, which relates to internal validity, not the generalizability problem highlighted in the question. Option C raises concerns about measurement error, which affects data reliability but doesn't address whether findings apply beyond the studied cases. The key study tip: When you see researchers making broad claims about "universal" effects based on studies of specific populations or contexts, immediately ask whether the scope conditions limit generalizability. Post-communist transitions represent a unique historical moment that may not provide lessons applicable to all economic development scenarios.

Question 4

A cross-national study finds a robust positive correlation between citizens' average level of political trust and the effectiveness of their government's bureaucracy. The study's author concludes that high levels of social and political trust cause governments to perform more effectively. What is the most significant potential problem of endogeneity in this causal claim?

  1. The definition of 'trust' and 'effectiveness' may vary significantly across different cultural contexts, leading to measurement issues.
  2. The causal direction may be reversed; citizens may develop higher levels of trust because their government's bureaucracy is effective and reliable. (correct answer)
  3. The sample of nations is likely biased, as countries with very low trust or effectiveness are often excluded due to data unavailability.
  4. A third variable, such as a country's level of economic development, likely causes both higher trust and a more effective bureaucracy.
Explanation: Endogeneity refers to problems where the independent variable is correlated with the error term. One of the primary forms of endogeneity is reverse causation. In this scenario, it is highly plausible that government performance causes trust, rather than the other way around. This poses a direct challenge to the author's causal claim. While (D) describes another endogeneity problem (omitted variable bias), reverse causation is a more direct and fundamental challenge to the stated causal arrow. (A) and (C) refer to measurement and sampling issues, not endogeneity.

Question 5

A researcher hypothesizes that the effect of a president's policy speech on public approval depends on the public's prior level of trust in government. For citizens with high trust, the speech is expected to increase approval. For citizens with low trust, the same speech is expected to have no effect or even decrease approval. The researcher's hypothesis is best described as a claim about:

  1. a spurious relationship, where trust is a confounding variable that causes both presidential speeches and public approval.
  2. a mediating pathway, where the speech affects trust, which in turn affects approval ratings.
  3. an interaction effect, where the causal impact of the speech is conditional upon the level of public trust. (correct answer)
  4. a tautological relationship, where presidential approval and trust in government are effectively measuring the same concept.
Explanation: This hypothesis describes an interaction effect, also known as moderation. The effect of the independent variable (the speech) on the dependent variable (approval) is not constant but depends on the value of a third variable (trust in government). The causal relationship is therefore conditional. It is not a mediating pathway (B), as trust is not described as being caused by the speech. It is not spurious (A) or tautological (D).

Question 6

A scholar uses process tracing to argue that a new environmental law was passed due to the strategic lobbying of a specific coalition of interest groups. To convincingly demonstrate this causal mechanism, which of the following pieces of evidence would be most crucial?

  1. A statistical analysis showing that countries with more environmental interest groups pass more environmental laws.
  2. Internal memos from the interest groups detailing their lobbying strategy and private communications from legislators showing that this strategy directly influenced their votes. (correct answer)
  3. Public opinion polls taken before and after the law was passed showing an increase in public support for environmental protection.
  4. An economic analysis demonstrating that the law produced significant, measurable improvements in environmental quality after its passage.
Explanation: Process tracing is a qualitative method focused on identifying and verifying the causal chain of events and mechanisms that link a cause to an outcome. It requires 'smoking gun' evidence that shows the process at work. Internal memos and private communications that directly link the lobbyists' actions to the legislators' decisions would be the most powerful evidence for the proposed mechanism. (A) is a cross-sectional statistical correlation, not process tracing. (C) and (D) relate to the context and consequences of the law, not the specific causal process of its passage.

Question 7

A study finds that cities with a higher proportion of residents who are immigrants have lower crime rates. The author concludes that immigrants are, as individuals, less likely to commit crimes. This conclusion is potentially invalid because it may be committing which type of error?

  1. Anachronism, by applying modern social standards to historical data.
  2. Selection bias, by only studying cities that attract immigrants.
  3. Ecological fallacy, by making an inference about individuals based on aggregate-level data. (correct answer)
  4. Spurious correlation, by failing to account for the effect of urban renewal projects.
Explanation: The ecological fallacy occurs when a researcher draws conclusions about individuals based solely on observations of groups. The finding that areas with more immigrants have lower crime rates does not logically require that individual immigrants are less prone to crime. It could be, for instance, that immigrant communities have stronger social cohesion that reduces crime among all residents, or that immigrants move to neighborhoods that are already safe for other reasons. The error is in the shift in the unit of analysis from the group (city) to the individual.

Question 8

To evaluate a new job-training program for unemployed individuals, a government agency compares the subsequent employment rates of individuals who voluntarily enrolled in the program to those who did not. The study finds that program participants have a significantly higher employment rate and concludes the program is effective. Which of the following is the most substantial threat to the validity of this conclusion?

  1. Selection bias, because individuals who voluntarily sign up for the program may be more motivated and proactive than those who do not. (correct answer)
  2. The Hawthorne effect, because participants may have improved their job-searching efforts simply because they knew they were being studied.
  3. The ecological fallacy, because group-level data on employment rates is used to infer individual-level success in finding a job.
  4. Omitted variable bias, because the study failed to control for the state of the national economy during the evaluation period.
Explanation: This is a classic case of selection bias. Because the participants were not randomly assigned to the program, there could be systematic pre-existing differences between the treatment group (volunteers) and the control group (non-volunteers). Volunteers are likely to be more motivated, have better existing skills, or possess other unobserved traits that make them more likely to find a job, regardless of the program. This inherent difference, not the program itself, could be driving the observed outcome.

Question 9

A political theorist argues: 'For a durable democratic state to emerge, a nation must first possess a strong and autonomous civil society. However, the presence of a strong civil society does not guarantee that a nation will transition to or maintain a democracy, as evidenced by several authoritarian states with vibrant non-governmental sectors.'

Based on the theorist's argument, the role of a strong civil society in the emergence of a durable democracy is best characterized as which of the following?

  1. A sufficient, but not necessary, condition.
  2. A necessary, but not sufficient, condition. (correct answer)
  3. Both a necessary and a sufficient condition.
  4. Neither a necessary nor a sufficient condition.
Explanation: The theorist states that a strong civil society must be present for democracy to emerge, which makes it a necessary condition. However, they also state that its presence does not guarantee democracy, meaning it is not a sufficient condition. Therefore, it is a necessary but not sufficient condition.

Question 10

A researcher runs a statistical analysis and finds that countries with higher levels of press freedom have, on average, lower levels of government corruption. The model does not include a variable measuring the strength of the judicial system. Given that a strong, independent judiciary is likely correlated with both higher press freedom and lower corruption, what is the most probable consequence of its exclusion?

  1. The estimated effect of press freedom on corruption is likely biased, making press freedom appear more important in reducing corruption than it actually is. (correct answer)
  2. The statistical significance of the relationship will be underestimated, making it harder to detect a true effect of press freedom.
  3. The model will have low external validity, meaning its conclusions cannot be generalized beyond the countries included in the sample.
  4. The exclusion introduces multicollinearity into the model, making the estimates for all included variables unstable and unreliable.
Explanation: This scenario describes omitted variable bias. The omitted variable (judicial strength) is positively correlated with the independent variable (press freedom) and negatively correlated with the dependent variable (corruption). By omitting it, the model incorrectly attributes some of the effect of the judiciary to press freedom. Therefore, the coefficient for press freedom will be biased, likely overstating its true causal effect on reducing corruption.

Question 11

A prominent theory of democratization suggests that increasing levels of economic development lead to the rise of an educated middle class, which in turn demands greater political representation, ultimately resulting in democratic institutions. In this causal chain, what role does the 'rise of an educated middle class' play?

  1. An independent variable that directly causes democratization.
  2. A moderating variable that changes the relationship between development and democracy.
  3. An intervening (or mediating) variable that explains the mechanism through which development affects democracy. (correct answer)
  4. A confounding variable that causes both economic development and democratic institutions independently.
Explanation: The theory describes a causal pathway: Economic Development → Rise of Middle Class → Democratization. The 'rise of an educated middle class' is the mechanism that connects the initial cause (development) to the final effect (democracy). In causal modeling, such a variable is known as an intervening or mediating variable.

Question 12

A political communication scholar argues that exposure to negative political advertising reduces a candidate's vote share, but that this effect is much stronger among independent voters than among voters who identify as strong partisans. In this causal hypothesis, a voter's partisan identification functions as what kind of variable?

  1. An intervening variable that links advertising exposure to vote choice.
  2. A dependent variable that is caused by exposure to negative advertising.
  3. A confounding variable that is the true cause of both advertising exposure and vote choice.
  4. A moderating variable that alters the strength of the relationship between advertising and vote choice. (correct answer)
Explanation: A moderating variable influences the strength or direction of a relationship between two other variables. Here, partisan identification is hypothesized to change the impact of negative advertising (the independent variable) on vote share (the dependent variable). The effect is strong for one group (independents) and weak for another (partisans). This is the definition of moderation or an interaction effect.

Question 13

A researcher wants to test the causal effect of a civics education course on high school students' political engagement. Compared to an observational study that compares students who chose to take the course with those who did not, why would a randomized controlled trial (RCT) provide a stronger basis for causal inference?

  1. An RCT allows for the use of more advanced statistical techniques to analyze the data.
  2. Random assignment to treatment and control groups ensures that, on average, the two groups are comparable on all potential confounding variables. (correct answer)
  3. An RCT is generally less expensive and can be completed more quickly than a long-term observational study.
  4. Observational studies can only establish correlation, whereas an RCT can prove causation with absolute certainty.
Explanation: The key strength of an RCT is random assignment. By randomly assigning students to either take the course (treatment) or not (control), the researcher ensures that there are no systematic differences between the groups on any other variable (e.g., prior interest in politics, parental influence, academic ability). This isolates the causal effect of the course itself. The observational design is weak because students who choose to take a civics course are likely already different from those who do not (selection bias). While causation is never proven with 'absolute certainty' (D), an RCT provides much stronger evidence than observational designs.

Question 14

To understand the causes of welfare state expansion, a researcher compares two countries. The countries are very different in most respects (e.g., culture, political system, history), but they both experienced rapid industrialization in the early 20th century and both subsequently developed large welfare states. The researcher tentatively concludes that rapid industrialization is a key cause of welfare state expansion. This comparative logic is an application of which of the following?

  1. Mill's Method of Agreement (correct answer)
  2. Mill's Method of Difference
  3. Regression discontinuity design
  4. Process tracing
Explanation: When you encounter questions about comparative research methods in political science, focus on identifying the logical structure of the comparison being made. This question tests your understanding of Mill's methods for causal inference through comparative analysis. The researcher is using Mill's Method of Agreement because they're comparing cases that differ in most respects but share two key similarities: rapid industrialization and welfare state development. Method of Agreement looks for common factors across otherwise different cases to identify potential causes. Here, the logic is: "If countries with very different cultures, political systems, and histories all developed welfare states after rapid industrialization, then industrialization might be the causal factor." Let's examine why the other options don't fit: (B) Mill's Method of Difference compares similar cases with different outcomes to isolate causal factors - the opposite structure of what's described here. (C) Regression discontinuity design is a quantitative method that exploits arbitrary cutoff points to create quasi-experimental conditions, which isn't relevant to this two-country comparison. (D) Process tracing involves detailed examination of causal mechanisms within cases, following the step-by-step process of how causes lead to effects, rather than comparing across cases. Study tip: Remember the core distinction between Mill's methods by their names - Method of Agreement seeks agreement (shared factors) among different cases, while Method of Difference examines differences between similar cases. When you see comparative studies emphasizing what diverse cases have in common, think Method of Agreement.

Question 15

A scholarship program is awarded to all high school students with a grade point average (GPA) of 3.50 or higher. A researcher compares the college completion rates of students with a 3.51 GPA (who received the scholarship) to students with a 3.49 GPA (who did not). This regression discontinuity design is a powerful tool for causal inference primarily because it assumes that:

  1. students just above and just below the arbitrary cutoff are, on average, nearly identical in all other relevant characteristics. (correct answer)
  2. the GPA cutoff of 3.50 was chosen randomly by the program administrators.
  3. all students who receive the scholarship will successfully complete college due to the financial assistance.
  4. GPA is the single most important predictor of college success, rendering other factors insignificant.
Explanation: Regression discontinuity design (RDD) is a powerful quasi-experimental method that exploits arbitrary cutoffs to estimate causal effects. When you see RDD questions, focus on the key assumption that makes this design work for causal inference. The strength of RDD lies in the assumption that individuals just above and below an arbitrary threshold are essentially identical except for their treatment status. In this scholarship example, students with a 3.51 GPA versus 3.49 GPA are likely very similar in motivation, ability, family background, and other characteristics that affect college completion. The tiny GPA difference is often due to random factors rather than systematic differences. This creates a "natural experiment" where treatment assignment (scholarship eligibility) is virtually random near the cutoff, allowing researchers to isolate the causal effect of the scholarship. Option A correctly identifies this core assumption - that students near the cutoff are nearly identical in all relevant characteristics except scholarship receipt. Option B is wrong because the cutoff doesn't need to be randomly chosen; it just needs to create similar groups on either side. Option C makes an unrealistic assumption about guaranteed success - RDD doesn't assume universal treatment effects. Option D incorrectly suggests other factors don't matter, when RDD actually controls for these factors through the similarity assumption near the cutoff. Remember: RDD's power comes from comparing very similar individuals who happen to fall on opposite sides of an arbitrary line. Look for this "local randomization" concept whenever you encounter regression discontinuity questions.

Question 16

The theory of democratic peace posits that democracies rarely, if ever, go to war with one another. The proposed causal mechanisms for this phenomenon are twofold: first, the institutional constraints of democratic governments (e.g., checks and balances, public accountability) make it difficult for leaders to initiate wars. Second, the shared norms and values among democracies foster trust and respect, leading to peaceful conflict resolution.

A critic of this theory argues that the observed peace between democracies since 1945 is not caused by their shared regime type, but by a confounding variable. Which of the following potential confounders represents the most significant alternative explanation for the democratic peace phenomenon during this period?

  1. The fact that most democratic nations are geographically distant from one another, reducing the opportunity for armed conflict.
  2. The global increase in international trade, which makes war between any two trading partners more costly, regardless of their regime type.
  3. The tendency for democratic countries to be wealthier, and wealthy countries are inherently less likely to engage in destructive wars.
  4. The shared security interests created by the Cold War, which aligned most major democracies in the Western bloc against a common Soviet threat. (correct answer)
Explanation: When analyzing theories in international relations, you need to distinguish between correlation and causation. The democratic peace theory claims that shared democratic institutions and values cause peace between democracies. However, critics argue that other factors might explain this correlation. Option D provides the strongest alternative explanation because the Cold War fundamentally reshaped global politics from 1945 onward. Most major democracies (US, UK, France, West Germany, Japan, etc.) found themselves allied against the Soviet Union, creating powerful shared security interests that transcended their regime type. This common external threat provided strong incentives for cooperation and peaceful dispute resolution among Western democracies, regardless of their internal political structures. Option A fails because geographic distance doesn't explain peace between nearby democracies like those in Western Europe, who historically fought frequently but stopped after 1945. Option B oversimplifies economic interdependence theory—while trade can reduce conflict, it doesn't account for the specific timing and pattern of democratic peace during the Cold War era. Option C incorrectly assumes wealth automatically prevents war; wealthy nations have historically engaged in costly conflicts when their interests diverged significantly. The key insight is temporal: the democratic peace phenomenon became pronounced precisely when the Cold War began, suggesting that shared strategic interests against a common adversary may be the real driver. When studying IR theories, always ask whether alternative explanations better account for the timing, scope, and specific patterns of the phenomena being explained.

Question 17

A comparative study of 20th-century social revolutions finds that the outcome occurred in Russia due to state collapse after a major war, in China due to a peasant-led insurgency, and in Iran due to the mobilization of urban networks against a modernizing autocrat. The observation that several different causal paths can lead to the same outcome is an example of which concept?

  1. Multifinality
  2. Path dependence
  3. Overdetermination
  4. Equifinality (correct answer)
Explanation: When you encounter questions about comparative research and causal patterns, focus on the relationship between causes and effects. This question tests your understanding of different ways multiple causal pathways can operate. The scenario describes three different causal mechanisms (state collapse, peasant insurgency, urban mobilization) all leading to the same outcome (social revolution). This illustrates equifinality - the principle that multiple different paths can lead to identical results. Think of it like reaching the same destination via different routes. Option A, multifinality, represents the opposite concept - when one cause leads to multiple different outcomes. If the question showed how state collapse led to revolution in one case but democratic transition in another, that would be multifinality. Option B, path dependence, refers to how early decisions or events constrain future possibilities, making certain outcomes more likely based on historical sequences. This doesn't apply here since we're comparing different causal paths, not how past events shaped current options. Option C, overdetermination, occurs when multiple causes simultaneously contribute to the same outcome in a single case. If the question had described Russia experiencing state collapse AND peasant insurgency AND urban mobilization all together, that would be overdetermination. The key distinction is that equifinality compares different cases with different causes producing the same result, while overdetermination involves multiple causes operating within the same case. Remember: equifinality = different roads to Rome; overdetermination = multiple forces pushing the same boulder.

Question 18

To evaluate a new job-training program for unemployed individuals, a government agency compares the subsequent employment rates of individuals who voluntarily enrolled in the program to those who did not. The study finds that program participants have a significantly higher employment rate and concludes the program is effective. Which of the following is the most substantial threat to the validity of this conclusion?

  1. Selection bias, because individuals who voluntarily sign up for the program may be more motivated and proactive than those who do not. (correct answer)
  2. The Hawthorne effect, because participants may have improved their job-searching efforts simply because they knew they were being studied.
  3. The ecological fallacy, because group-level data on employment rates is used to infer individual-level success in finding a job.
  4. Omitted variable bias, because the study failed to control for the state of the national economy during the evaluation period.
Explanation: This is a classic case of selection bias. Because the participants were not randomly assigned to the program, there could be systematic pre-existing differences between the treatment group (volunteers) and the control group (non-volunteers). Volunteers are likely to be more motivated, have better existing skills, or possess other unobserved traits that make them more likely to find a job, regardless of the program. This inherent difference, not the program itself, could be driving the observed outcome.

Question 19

A political theorist argues: 'For a durable democratic state to emerge, a nation must first possess a strong and autonomous civil society. However, the presence of a strong civil society does not guarantee that a nation will transition to or maintain a democracy, as evidenced by several authoritarian states with vibrant non-governmental sectors.'

Based on the theorist's argument, the role of a strong civil society in the emergence of a durable democracy is best characterized as which of the following?

  1. A sufficient, but not necessary, condition.
  2. A necessary, but not sufficient, condition. (correct answer)
  3. Both a necessary and a sufficient condition.
  4. Neither a necessary nor a sufficient condition.
Explanation: The theorist states that a strong civil society must be present for democracy to emerge, which makes it a necessary condition. However, they also state that its presence does not guarantee democracy, meaning it is not a sufficient condition. Therefore, it is a necessary but not sufficient condition.

Question 20

A researcher runs a statistical analysis and finds that countries with higher levels of press freedom have, on average, lower levels of government corruption. The model does not include a variable measuring the strength of the judicial system. Given that a strong, independent judiciary is likely correlated with both higher press freedom and lower corruption, what is the most probable consequence of its exclusion?

  1. The estimated effect of press freedom on corruption is likely biased, making press freedom appear more important in reducing corruption than it actually is. (correct answer)
  2. The statistical significance of the relationship will be underestimated, making it harder to detect a true effect of press freedom.
  3. The model will have low external validity, meaning its conclusions cannot be generalized beyond the countries included in the sample.
  4. The exclusion introduces multicollinearity into the model, making the estimates for all included variables unstable and unreliable.
Explanation: This scenario describes omitted variable bias. The omitted variable (judicial strength) is positively correlated with the independent variable (press freedom) and negatively correlated with the dependent variable (corruption). By omitting it, the model incorrectly attributes some of the effect of the judiciary to press freedom. Therefore, the coefficient for press freedom will be biased, likely overstating its true causal effect on reducing corruption.