Question 1

Many surveys are conducted over the phone.Which of the following would be most likely to cast doubt on the external validity of these studies?

Accepted Answer

If all of the people participating in the survey own telephones, then the results may not be representative of the entire population because some people may not have access to phones. This can cast doubt on the external validity of the study, as it may not accurately reflect the opinions or behaviors of the general population.

Question 2

How is an observational study different from an experiment?

Accepted Answer

In an observational study, researchers observe and gather data on variables as they naturally occur without controlling them. In contrast, in an experiment, researchers manipulate and control variables to test cause-and-effect relationships. Therefore, choice D is the correct option as it accurately describes the difference between observational studies and experiments.

Question 3

Suppose we find that there is a correlation between illegal drug use and suicide.By itself, this would not prove that illegal drug use causes suicide, because there could be a confounding variable.What is the most likely candidate?

Accepted Answer

Depression is a common confounding variable in the relationship between illegal drug use and suicide. Depression is a known risk factor for suicide and is also linked to drug abuse. Therefore, it is possible that the correlation between drug use and suicide is actually due to the influence of depression.

Question 4

Suppose we want to know how the population of an anthill varies over time.It is difficult to make a direct observation of how many ants are in an anthill, so which of the following would be the best proxy variable?

Accepted Answer

The rate at which ants exit the anthill can serve as a proxy for the population size, as a larger population might result in more ants exiting to forage or perform other tasks. This is a direct activity that correlates with the number of ants inside the anthill, making it a suitable proxy variable for estimating population variations over time.

Question 5

Suppose we want to study how a drug affects someone's happiness.It is difficult to make a direct observation of how happy someone is, so which of the following would be the best proxy variable?

Accepted Answer

Frequency of smiling is the best proxy variable as it is directly related to one's level of happiness. A person is more likely to smile when they are happy, and less likely to smile when they are not. Time spent exercising, use of pain medication, alcohol consumption, and frequency of social interaction are not necessarily directly related to a person's level of happiness.

Question 6

Many psychological studies are conducted on college campuses.Which of the following would be most likely to cast doubt on the external validity of these studies?

Accepted Answer

If all of the subjects in the study are college students, it may not be possible to generalize the findings to the wider population as college students may differ from the general population in significant ways. This would reduce the external validity of the studies.

Question 7

Is it generally more difficult to draw causal conclusions from an experiment or from an observational study?

Accepted Answer

It is generally more difficult to draw causal conclusions from an observational study because such studies do not involve the manipulation of variables or the random assignment of participants to different conditions, which are key elements in establishing causality. Experiments, by design, control for confounding variables and allow for the establishment of cause-and-effect relationships more directly.

Question 8

Sometimes it is difficult to establish a causal relationship between two correlating variables due to the presence of a third variable that correlates with both of them.This third variable is called a _____ variable.

Accepted Answer

A confounding variable is a variable that is related to both the independent and dependent variables and can often create a false relationship or obscure the true relationship between them. For example, a study might find a correlation between alcohol consumption and heart disease, but this relationship may be confounded by the fact that individuals who drink alcohol also have other unhealthy behaviors, such as smoking or a poor diet.

Question 9

Which of the following could be a contributing factor for failing a class?

Accepted Answer

The answer of Which of the following could be a...

Question 10

Suppose that a study finds a causal relationship between two variables.The study has external validity if its findings:

Accepted Answer

External validity refers to the ability to generalize study findings beyond the sample of individuals that were studied. Option D states that the findings apply to the general population, which would indicate strong external validity. The other options do not necessarily relate to external validity.

Question 11

Assuming that two things are causally related simply because they correlate is most similar to committing which logical fallacy?

Accepted Answer

Assuming that two things are causally related simply based on correlation is committing the post hoc fallacy. This fallacy asserts that because one event happened before another event, the first event caused the second event. However, just because two events occur together or in succession does not necessarily mean that one caused the other.

Question 12

Compared with experiments, one drawback of observational studies is that they lack:

Accepted Answer

Observational studies do not have randomly assigned control groups, which are crucial for establishing causation in experimental studies.

Question 13

In order to establish a statistical correlation between a and E, we compare two groups that are basically the same, except that a is present in one and not present in the other.If it turns out that E is more common when a is present, is this enough to show that they correlate?

Accepted Answer

A statistical correlation can be established through comparing two groups that are the same except for one variable. In this scenario, if E is more common when a is present, there may be a correlation between a and E. However, the significance of this correlation would depend on the size of the difference between the two groups. A larger difference would suggest a stronger correlation, while a smaller difference may not be statistically significant. Therefore, choice B is the correct answer. Choices A, C, D, and E are all incorrect. A is incorrect because even a slight difference does not necessarily prove a correlation. C is incorrect because a correlation is a statistical relationship, not necessarily a causal one. D is incorrect because the presence of a in both groups would be necessary to establish causality, not correlation. E is incorrect because equality in the presence of E is not required for a correlation to exist.

Question 14

In order to establish a statistical correlation between a and E, we need to compare two groups that are basically the same, except that a is present in one and not present in the other.Given that the individual members of these groups might vary quite a lot, how can we make it likely that, apart from the presence of a, the two groups are basically the same?

Accepted Answer

Using large, randomly chosen groups increases the likelihood that the two groups will be similar apart from the variable being studied (in this case, a). This helps to reduce the impact of individual differences within each group, and increases the chances of obtaining meaningful information about the correlation between a and E. Small randomly chosen groups may not be representative enough and matching individuals in both groups would not account for unknown confounding factors. Option E is incorrect because it is possible to create similar groups even though there may be some variability within the groups.

Question 15

Suppose we find that there is a correlation between people wearing T-shirts and people having flies in their homes.By itself, this would not prove that wearing T-shirts attracts insects, because there could be a confounding variable.What is the most likely candidate?

Accepted Answer

The most likely confounding variable is changing seasons (C). This is because both the tendency to wear T-shirts and the presence of flies in homes can increase during warmer months, suggesting that the correlation might not be directly causal but rather both influenced by the warmer weather.

Question 16

In order to establish a statistical correlation between a and E, we compare the presence of E in two groups, one in which a is present (called the _____ group) and one in which a is not present (called the _____ group).

Accepted Answer

The experimental group is the group where the variable of interest (a) is present, while the control group is the group where the variable of interest is not present. Therefore, the best choice is E, where the experimental group is paired with the presence of a and the control group is paired with the absence of a.

Question 17

Is a correlation between A and B enough to show that A causes B?

Accepted Answer

Correlation simply shows a relationship between two variables, but it does not prove causation. There could be other factors that are affecting both A and B, making their correlation coincidental or spurious. To establish causation, further evidence such as experimental data or elimination of alternative explanations is required.

Question 18

Are the motions of the planets studied by means of observational studies or experiments?

Accepted Answer

The motions of planets, including Earth, are studied through observational studies because direct experiments on planetary motion are not feasible due to the vast scales and forces involved. Scientists observe and record the movements of planets and use these observations to develop and refine models and theories of planetary motion.

Question 19

Sometimes a variable cannot be studied directly, but can be studied indirectly by means of some other variable.This other variable is a called a _____ variable.

Accepted Answer

A proxy variable is used to indirectly measure a variable of interest. It serves as a substitute for the variable that cannot be directly measured.

Question 20

Suppose we find that there is a correlation between the cleanliness of a student's room and how much time that student spends studying.By itself, this would not prove that having a clean room causes students to study longer, because there could be a confounding variable.What is the most likely candidate?

Accepted Answer

The self-discipline of the student is the most likely confounding variable because a student who is already disciplined may be more likely to keep their room clean and also more likely to spend more time studying. Conversely, a student who lacks self-discipline may have a messy room and also spend less time studying. Therefore, self-discipline is a potential confounding variable that could impact the relationship between cleanliness and study habits.

Quiz 14: Statistical Reasoning

Many surveys are conducted over the phone.Which of the following would be most likely to cast doubt on the external validity of these studies?

How is an observational study different from an experiment?

Suppose we find that there is a correlation between illegal drug use and suicide.By itself, this would not prove that illegal drug use causes suicide, because there could be a confounding variable.What is the most likely candidate?

Suppose we want to know how the population of an anthill varies over time.It is difficult to make a direct observation of how many ants are in an anthill, so which of the following would be the best proxy variable?

Suppose we want to study how a drug affects someone's happiness.It is difficult to make a direct observation of how happy someone is, so which of the following would be the best proxy variable?

Many psychological studies are conducted on college campuses.Which of the following would be most likely to cast doubt on the external validity of these studies?

Is it generally more difficult to draw causal conclusions from an experiment or from an observational study?

Sometimes it is difficult to establish a causal relationship between two correlating variables due to the presence of a third variable that correlates with both of them.This third variable is called a _____ variable.

Which of the following could be a contributing factor for failing a class?

Suppose that a study finds a causal relationship between two variables.The study has external validity if its findings:

Assuming that two things are causally related simply because they correlate is most similar to committing which logical fallacy?

Compared with experiments, one drawback of observational studies is that they lack:

In order to establish a statistical correlation between a and E, we compare two groups that are basically the same, except that a is present in one and not present in the other.If it turns out that E is more common when a is present, is this enough to show that they correlate?

Suppose we find that there is a correlation between people wearing T-shirts and people having flies in their homes.By itself, this would not prove that wearing T-shirts attracts insects, because there could be a confounding variable.What is the most likely candidate?

In order to establish a statistical correlation between a and E, we compare the presence of E in two groups, one in which a is present (called the _ group) and one in which a is not present (called the _ group) .

Is a correlation between A and B enough to show that A causes B?

Are the motions of the planets studied by means of observational studies or experiments?

Sometimes a variable cannot be studied directly, but can be studied indirectly by means of some other variable.This other variable is a called a _____ variable.

Quiz 14: Statistical Reasoning

Many surveys are conducted over the phone.Which of the following would be most likely to cast doubt on the external validity of these studies?

How is an observational study different from an experiment?

Suppose we find that there is a correlation between illegal drug use and suicide.By itself, this would not prove that illegal drug use causes suicide, because there could be a confounding variable.What is the most likely candidate?

Suppose we want to know how the population of an anthill varies over time.It is difficult to make a direct observation of how many ants are in an anthill, so which of the following would be the best proxy variable?

Suppose we want to study how a drug affects someone's happiness.It is difficult to make a direct observation of how happy someone is, so which of the following would be the best proxy variable?

Many psychological studies are conducted on college campuses.Which of the following would be most likely to cast doubt on the external validity of these studies?

Is it generally more difficult to draw causal conclusions from an experiment or from an observational study?

Sometimes it is difficult to establish a causal relationship between two correlating variables due to the presence of a third variable that correlates with both of them.This third variable is called a _____ variable.

Which of the following could be a contributing factor for failing a class?

Suppose that a study finds a causal relationship between two variables.The study has external validity if its findings:

Assuming that two things are causally related simply because they correlate is most similar to committing which logical fallacy?

Compared with experiments, one drawback of observational studies is that they lack:

In order to establish a statistical correlation between a and E, we compare two groups that are basically the same, except that a is present in one and not present in the other.If it turns out that E is more common when a is present, is this enough to show that they correlate?

Suppose we find that there is a correlation between people wearing T-shirts and people having flies in their homes.By itself, this would not prove that wearing T-shirts attracts insects, because there could be a confounding variable.What is the most likely candidate?

In order to establish a statistical correlation between a and E, we compare the presence of E in two groups, one in which a is present (called the _____ group) and one in which a is not present (called the _____ group) .

Is a correlation between A and B enough to show that A causes B?

Are the motions of the planets studied by means of observational studies or experiments?

Sometimes a variable cannot be studied directly, but can be studied indirectly by means of some other variable.This other variable is a called a _____ variable.

In order to establish a statistical correlation between a and E, we compare the presence of E in two groups, one in which a is present (called the _ group) and one in which a is not present (called the _ group) .