Question 1

A state set a minimum grade point average requirement for students receiving financial aid starting in 2005 .A researcher compared college graduation rates before and after 2005 in both that state and other states in the region .This type of research is

Accepted Answer

This research design is a difference-in-differences study because it compares outcomes (college graduation rates) before and after a policy change (minimum GPA requirement for financial aid) between a treatment group (the state with the policy change) and a control group (other states in the region without the policy change).

Question 2

The effect of adding fluoride to a community's water supply was tested by comparing annual records of cavities per patient in local dentists' offices for six years before and four years after the fluoride was addeD .This is an example of which type of research?

Accepted Answer

This is an example of an interrupted time series research design, where measurements are taken repeatedly on the same subjects both before and after a treatment (in this case, the addition of fluoride to the water supply) to determine the treatment's effect.

Question 3

An evaluator was hired after a homeless shelter started offering assistance with applying for food stamps .She compared the daily caloric intake of the homeless at that shelter and a nearby shelter not offering application assistance .This study uses

Accepted Answer

A

Question 4

______ tend to have stronger generalizability, whereas _____ tend to provide stronger evidence of causation.

Accepted Answer

Randomized experiments tend to provide stronger evidence of causation due to their controlled and random assignment of subjects, which minimizes biases. Quasi-experiments, on the other hand, often have stronger generalizability because they are conducted in more natural settings, but they lack the random assignment feature.

Question 5

A criminal justice professor compared crime rates in cities where police departments adopted performance measurement systems to those that did not, both before and after the systems were implementeD .This type of research is called

Accepted Answer

This research is a quasi-experiment because it involves comparing groups based on a pre-existing condition (the adoption of performance measurement systems by some police departments) rather than randomly assigning participants to groups.

Question 6

A school compared the grades of students with disabilities while they were in separate classrooms and a year later when the state required integrating these students into mainstream classrooms .What type of research is this?

Accepted Answer

This is a before-after study because it compares the grades of students with disabilities before and after a specific intervention, which in this case is the integration into mainstream classrooms.

Question 7

Students in a school system with scores below 70 on a diagnostic test are required to attend an early morning math program .At the end of the year, researchers compared the math grades for these students with those of students who scored 70 or above on the initial diagnostic test, controlling statistically for diagnostic test score .This type of research uses

Accepted Answer

This type of research uses Regression Discontinuity design, as it compares outcomes (math grades) on either side of a cutoff score (70) on the diagnostic test, controlling for that score.

Question 8

Researchers used a flip of the coin to assign participants to view either a one-minute public information video about the environment or a control video of the same duration that showed only highlights of entertainment news .The researchers then observed how many participants in each group deposited small water bottles (which they had been given at the outset) into the recycle bin as opposed to an adjacent trash bin .This research involves a(n)

Accepted Answer

This is a randomized experiment because participants were randomly assigned to different groups (environmental video vs. control video) to observe the effect of the intervention (type of video watched) on a specific outcome (recycling behavior). Random assignment is a key feature of randomized experiments.

Question 9

Researchers studied the labor market in Miami before and after the Mariel Boatlift in 1980, during which a large influx of Cubans arrived in Miami looking for jobs .The shock of the Mariel Boatlift on the local labor supply was exogenous to wages in Miami .This is an example of a(n)

Accepted Answer

The Mariel Boatlift's effect on Miami's labor market is considered a natural experiment because the event occurred independently of the local labor market conditions, providing an opportunity to study its impact without the researchers having to manipulate variables.

Question 10

A study using the General Social Survey tested whether individuals who are members of a club report greater life satisfaction .What type of research design is this?

Accepted Answer

This is an observational study because it involves observing subjects in their natural environment without manipulating any variables. The researchers are simply collecting data on individuals' club membership status and their reported life satisfaction, not intervening or altering the participants' experiences.

Quiz 15: Natural and Quasi Experiments