80 Questions
In the RAND Health Insurance Experiment (HIE), how many families were randomly assigned to different insurance coverage plans?
2,000 families
What was the duration of the STAR experiment in Tennessee?
Four years
What was the purpose of the modified tablet treatment group in Carter et al.'s study?
To examine the impact of tablet usage on academic performance
Which of the following was NOT an insurance coverage plan in the RAND Health Insurance Experiment?
80% co-payment
What was the role of part-time teacher’s aides in the STAR experiment in Tennessee?
To work with the primary teacher in small classes
Which experiment cost about $12 million and involved a cohort of kindergartners?
Project STAR Tennessee
What differentiated the treatment group from the 'modified tablet' group in Carter et al.'s study?
'Modified tablet' group could only use tablets flat on desk
What was unique about the class sizes in the STAR experiment?
'Regular classes' with part-time teacher's aides had 13-17 children
What does the identification problem in causal analysis aim to measure?
The difference in expected outcomes between treatment and control groups
How does random assignment help address the selection bias?
It eliminates the selection bias
In a randomized experiment, how is the treatment assignment determined?
By a lottery
What is the purpose of using randomization in experimental design?
To ensure that each subject has an equal chance of being assigned to treatment or control groups
How does random assignment impact the causal inference process in experiments?
It strengthens causal inference by reducing bias
What is the primary goal of randomization in a causal analysis?
To minimize bias in estimating causal effects
Why is random assignment considered essential in experimental design?
To reduce the influence of confounding variables
How does random assignment affect the interpretation of cause-and-effect relationships?
It simplifies interpretation by removing confounding factors
What does random assignment in a randomized experiment make independent of potential outcomes?
Treatment
In a randomized experiment, what does the independence between potential outcomes and treatment imply?
Equal expected outcomes for each treatment group
What does AT T represent in the context of a randomized experiment?
Difference in expected outcomes between treatment groups
What problem does random assignment solve in experimental design?
Selection bias
What does E[Y1i − Y0i |Di = 1] represent in a randomized experiment?
Average effect in the whole population
In regression analysis of experiments, what is assumed to be constant?
(Y1i − Y0i)
What is meant by AT E in the context of a randomized experiment?
$E[Y1i - Y0i]$
How does randomization make treatment and no-treatment groups comparable in pre-treatment characteristics?
$E[Y0i|Di=0] = E[Y0i|Di=1] = E[Y0i]$
What is a common question to ask about a randomized experiment's design?
If the treatment groups have different characteristics
What is a key aspect to test when examining the credibility of an experimental design?
Statistical significance of differences between treatment groups
Which characteristic of highly disciplined students contributes to the absence of compliance issues in the study?
They have better time management skills
What impact does the ability to access electronic devices during class have on students' learning outcomes?
A combination of positive and negative effects
In a randomized experiment, what does it mean if pre-treatment outcomes and covariates are balanced across treatment groups?
The randomization process was successful
What aspect makes the United States Military Academy an ideal setting for a randomized trial to evaluate online teaching?
The curriculum is uniform and graded events are identical
What did Kofoed et al. do to control for instructor effects in their experiment on online learning?
Each instructor taught half their load online and half in-person
What is the main goal of setting up a randomized trial for evaluating online teaching at the United States Military Academy?
To assess the impact of online teaching on academic performance
What does the regression model presented in the text help to estimate?
The treatment effect
In the context of the classical linear regression model, what does mean independence of errors imply?
OLS estimation of the treatment effect is unbiased
What is the role of randomization in ensuring mean independence in the classical linear regression model?
It ensures that E[ηi |Di = 1] − E[ηi |Di = 0] = 0
Why is controlling for other covariates X not needed in the randomization setup described in the text?
Because E[ηi |Di = 1] − E[ηi |Di = 0] = 0 under randomization
What does the selection bias in experiments amount to according to the text?
Difference between treatment and no-treatment groups
In the context of regression analysis of experiments, what does E[Yi |Di = 1] − E[Yi |Di = 0] represent?
Treatment effect τ
What is the main implication of the constant-effect assumption in evaluating treatment effects?
E[Yi |Di = 1] − E[Yi |Di = 0] = τ
Based on the text, why does OLS provide unbiased estimates for the treatment effect τ?
E[ηi |Di = 1] − E[ηi |Di = 0] = 0 after randomization
What is the importance of testing for statistically significant differences in pre-treatment outcomes and other covariates across treatment groups in a randomized experiment?
To ensure that randomization successfully balanced the subjects characteristics across treatment groups.
Why is the United States Military Academy at West Point considered an ideal setting for a randomized trial to evaluate online teaching?
Students have little control over their academic schedules and peer networks, making random assignment feasible.
What are the potential positive and negative effects of using electronic devices on students' learning outcomes?
Positive: ability to take notes faster. Negative: potential distractions from web-surfing.
How did Kofoed et al. control for instructor effects in their experiment on online learning?
Each instructor taught half of their four section teaching load online and half in-person.
What does randomized assignment in a randomized experiment ensure the independence of?
Potential outcomes from treatment assignment.
What is the main implication of the constant-effect assumption in evaluating treatment effects?
That the treatment effect is consistent across all subjects.
Why is random assignment considered essential in experimental design?
To ensure that treatment and no-treatment groups are comparable in pre-treatment characteristics.
What differentiated the treatment group from the 'modified tablet' group in Carter et al.'s study on the impact of electronic devices on learning outcomes?
The 'modified tablet' group was randomly allowed to access their devices during class.
What was the main difference between the treatment group and the 'modified tablet' group in Carter et al.'s study?
The treatment group could use laptops and tablets without restriction, while the 'modified tablet' group was only allowed to use tablets flat on the desk surface.
What was the unique aspect of the experimental design in the RAND Health Insurance Experiment (HIE)?
The HIE randomly assigned 2,000 families from six US cities to different insurance coverage plans.
In the STAR experiment in Tennessee, what were the three treatments that students were randomly assigned to?
Small classes with 13-17 children, regular classes with 22-25 children, and part-time teacher’s aide regular classes with full-time teacher’s aide.
What was the main goal of the STAR experiment in Tennessee?
To estimate the effects of smaller classes in primary school.
What differentiated the treatment group from the 'modified tablet' group in Carter et al.'s study?
The treatment group could use laptops and tablets without restriction, while the 'modified tablet' group was only allowed to use tablets flat on the desk surface.
What was the role of the part-time teacher’s aides in the STAR experiment in Tennessee?
Part-time teacher’s aides were involved in the regular classes with full-time teacher’s aides.
What differentiated the treatment group from the 'modified tablet' group in the study by Carter et al. (2017)?
The treatment group could use laptops and tablets without restriction, while the 'modified tablet' group was only allowed to use tablets flat on the desk surface.
What was the main implication of the constant-effect assumption in evaluating treatment effects?
The constant-effect assumption simplifies the interpretation of treatment effects by assuming the effect is consistent across all observations.
Explain the identification problem in causal analysis as mentioned in the text.
The identification problem aims to measure the causal effect by comparing outcomes under different treatment conditions.
How does random assignment help address the selection bias in experiments?
Random assignment helps mitigate selection bias by ensuring that treatment and control groups are comparable on average before treatment.
What role does randomization play in ensuring mean independence in the classical linear regression model?
Randomization ensures that treatment assignment is independent of potential outcomes, leading to mean independence in the regression model.
How does random assignment affect the interpretation of cause-and-effect relationships in experiments?
Random assignment allows for a clearer interpretation of cause-and-effect relationships by minimizing the influence of confounding variables.
What does random assignment in a randomized experiment make independent of potential outcomes?
Random assignment makes the treatment assignment independent of potential outcomes, ensuring a fair comparison between treatment and control groups.
What problem does random assignment solve in experimental design?
Random assignment solves the issue of selection bias by ensuring that treatment and control groups are comparable on average before the treatment is applied.
Explain the impact of random assignment on the causal inference process in experiments.
Random assignment strengthens causal inference by providing a more robust basis for attributing observed outcomes to the treatment.
What aspect of highly disciplined students contributes to the absence of compliance issues in a study?
The high discipline of students contributes to compliance as they are more likely to adhere to the study protocols and treatment conditions.
What is the implication of random assignment in terms of potential outcomes and treatment?
Independence
What does AT T represent in the context of experimental design?
Average Treatment Effect
How does random assignment solve the selection problem in experiments?
Makes treatment and no-treatment groups comparable
What does E[Y1i - Y0i |Di = 1] represent in a randomized experiment?
Average Treatment Effect
In the context of regression analysis of experiments, what does Y1i - Y0i = τ being constant imply?
Constant treatment effect
What is the role of randomization in ensuring mean independence in the classical linear regression model?
Prevents correlation between treatment assignment and potential outcomes
How does randomization impact the interpretation of cause-and-effect relationships?
Ensures causal inference
What is the main goal of setting up a randomized trial for evaluating online teaching?
Evaluating the treatment effect
Explain the role of randomization in ensuring mean independence in the classical linear regression model.
Randomization ensures mean independence by implying that E[ηi |Di = 1] − E[ηi |Di = 0] = 0.
What does the selection bias in experiments amount to according to the text?
Selection bias amounts to the correlation between Di and ηi.
How does random assignment help address the selection bias?
Random assignment helps address selection bias by making the treatment and no-treatment groups comparable in pre-treatment characteristics.
What is the main implication of the constant-effect assumption in evaluating treatment effects?
The main implication is that under the constant-effect assumption, the treatment effect is given by τ.
What does the identification problem in causal analysis aim to measure?
The identification problem aims to measure the treatment effect τ.
What is the primary goal of randomization in a causal analysis?
The primary goal of randomization is to ensure that E[ηi |Di = 1] − E[ηi |Di = 0] = 0.
What does E[Yi |Di = 1] − E[Yi |Di = 0] represent in the context of regression analysis of experiments?
E[Yi |Di = 1] − E[Yi |Di = 0] represents the treatment effect τ.
Why is controlling for other covariates X not needed in the randomization setup described in the text?
Controlling for other covariates X is not needed because randomization ensures mean independence, making OLS unbiased for τ.
Explore a study by Carter et al (2017) on the effects of computer usage on academic performance, focusing on two treatment groups where students were allowed to use laptops and tablets freely or only tablets placed flat on the desk. Learn about the randomized trial at the United States Military Academy and its findings.
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