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Which of the following is not a common difficulty associated with the double-blind study protocol?
In a double-blind protocol, both the research participants and the researchers engaging in the study are unaware of which participants are in the control group and which are in the experimental group. This actually makes subsequent meta-analysis of the double-blinded results easier, as a correctly applied double-blindness will remove any of the researcher's biases from the results.
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Melanie is a regular customer at a gun range, where she shoots paper targets with three different types of guns: a rifle, a pistol, and a shotgun. When firing the rifle, Melanie notices that her shots nearly always hit the target, but are evenly spread out throughout the paper's surface. When firing the pistol, Melanie's shots are all grouped within a few inches of each other, with the group overlaying the bull’s-eye on the target. When firing the shotgun, Melanie's shots are also tightly grouped, but the groups of shots are all slightly above the bull’s-eye. Which of the following terms is best describes Melanie's performance with the shotgun compared to her performance with the pistol?
Reliability is the ability of a measure, test, or effect to produce the same result upon repeated trials. In this case reliability was analogous to the grouping of shots on the target irrespective of the placement of the group. Validity is the ability of a test to measure what it is intended to measure or of a treatment to produce the effect it is purported to produce. In this case validity was analogous to the placement of shots on the target—the closer to the bull’s-eye, the more valid the shots.
In the scenario, the shots from the pistol—which hit both the target on the bull’s-eye and were grouped closely together—are valid and reliable. On the other hand, the shotgun shots—which are only grouped together but are not accurate to the bull’s-eye—are equally reliable but less valid.
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A sample of players on a baseball team are chosen to be drug tested. Which of the following methods could league officials use to ensure that the players are randomly selected?
Random selection allows all of the players on the team to have an equal chance of being chosen for testing. Choosing to test only players of a certain age or position, or only testing those that volunteer or have reached a certain statistical benchmark, would exclude a number of the players on the roster from having a chance to be chosen.
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Dana is participating in a study that asks her to press a red button every time the computer screen in front of her shows a letter X.
The computer screen shows a letter "T." Dana presses the red button. Dana's response is considered to be which of the following?
A false alarm is a response that says the target stimulus (in this case, the letter X) has been detected when that stimulus is not present.
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Dr. Crawford believes she has invented a pill to help with student memorization. For a trial experiment, she gathered two groups of twenty students. She gave the twenty students in Group A the “smart pill”, and the twenty students in Group B a sugar pill. After waiting five minutes, both groups of students were given a list of forty words, and were instructed to memorize the entire list in any order. The students were given five minutes to memorize the list. The students were then asked to verbally recite all of the words they could remember in any order within three minutes.
Group A recited an average of fifteen words, while Group B recited an average of ten words.
In this experiment, what is the independent variable?
The independent variable is what the researcher manipulates in order to test his or her hypothesis. In this experiment, Dr. Smart gave one group the smart pill and the other group a sugar pill in order to evaluate the smart pill's effect on student memorization.
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Dr. Crawford believes she has invented a pill to help with student memorization. For a trial experiment, she gathered two groups of twenty students. She gave the twenty students in Group A the “smart pill”, and the twenty students in Group B a sugar pill. After waiting five minutes, both groups of students were given a list of forty words, and were instructed to memorize the entire list in any order. The students were given five minutes to memorize the list. The students were then asked to verbally recite all of the words they could remember in any order within three minutes.
Group A recited an average of fifteen words, while Group B recited an average of ten words.
In this experiment, what is the dependent variable?
The dependent variable is the item actually being measured or analyzed the support or reject the hypothesis. The dependent variable measures the effect of the independent variable.
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Dr. Crawford believes she has invented a pill to help with student memorization. For a trial experiment, she gathered two groups of twenty students. She gave the twenty students in Group A the “smart pill”, and the twenty students in Group B a sugar pill. After waiting five minutes, both groups of students were given a list of forty words, and were instructed to memorize the entire list in any order. The students were given five minutes to memorize the list. The students were then asked to verbally recite all of the words they could remember in any order within three minutes.
Group A recited an average of fifteen words, while Group B recited an average of ten words.
Group A is the __________.
The experimental group is the group assigned to measure the effect of the independent variable. Students in Group A were given the smart pill, and thus their results will be analyzed to measure the effect it had on student memorization.
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Dr. Crawford believes she has invented a pill to help with student memorization. For a trial experiment, she gathered two groups of twenty students. She gave the twenty students in Group A the “smart pill”, and the twenty students in Group B a sugar pill. After waiting five minutes, both groups of students were given a list of forty words, and were instructed to memorize the entire list in any order. The students were given five minutes to memorize the list. The students were then asked to verbally recite all of the words they could remember in any order within three minutes.
Group A recited an average of fifteen words, while Group B recited an average of ten words.
Group B is the _________.
The control group is the group assigned to provide a comparison to the experimental group’s results, in order to measure the effect of the independent variable. Students in Group B were given a sugar pill instead of the smart pill to measure the effect on how many words students could properly recite.
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Dr. Crawford believes she has invented a pill to help with student memorization. For a trial experiment, she gathered two groups of twenty students. She gave the twenty students in Group A the “smart pill”, and the twenty students in Group B a sugar pill. After waiting five minutes, both groups of students were given a list of forty words, and were instructed to memorize the entire list in any order. The students were given five minutes to memorize the list. The students were then asked to verbally recite all of the words they could remember in any order within three minutes.
Group A recited an average of fifteen words, while Group B recited an average of ten words.
What is Dr. Smart’s null hypothesis?
The null hypothesis suggests that the independent variable has no effect in the experiment. If Dr. Crawford’s null hypothesis is supported, then her smart pill has virtually no effect on student memorization. The goal is to reject the null hypothesis with results from the experiment.
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Dr. Crawford believes she has invented a pill to help with student memorization. For a trial experiment, she gathered two groups of twenty students. She gave the twenty students in Group A the “smart pill”, and the twenty students in Group B a sugar pill. After waiting five minutes, both groups of students were given a list of forty words, and were instructed to memorize the entire list in any order. The students were given five minutes to memorize the list. The students were then asked to verbally recite all of the words they could remember in any order within three minutes.
Group A recited an average of fifteen words, while Group B recited an average of ten words.
What sort of experimental design is this?
Independent measures designs describe an experiment in which there are two or more separate groups. In Dr. Crawford’s experiment, the two groups are the students in Group A and Group B. The students do not overlap groups, and are only exposed to one of the two conditions during the experiment.
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After much success with her initial experiments (i.e. Groups A and B) and pilot test, Dr. Crawford wanted to further test the effects of a “smart pill." She recruited a new group of twenty students, Group C, for this next experiment. In the first trial, she gave the students the smart pill, and then waited five minutes to give them the list of forty words. Students were instructed to memorize the list in any order and were given five minutes to study it. The students were then asked to verbally recite all of the words they could remember within three minutes. One week later, Dr. Crawford repeated the experiment with the same group and same list of words. However, on the second trial, students were given the sugar pill instead of the smart pill.
On the first trial, students from Group C recalled an average of seventeen words. On the second trial, students recalled an average of twenty words.
Which of the following experimental designs best describes this particular study?
The students in Group C undergo the experiment two separate times, and experience both conditions. No other students than the 20 in Group C are used in this experiment. They act as both the control group and the experimental group.
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After much success with her initial experiments (i.e. Groups A and B) and pilot test, Dr. Crawford wanted to further test the effects of a “smart pill." She recruited a new group of twenty students, Group C, for this next experiment. In the first trial, she gave the students the smart pill, and then waited five minutes to give them the list of forty words. Students were instructed to memorize the list in any order and were given five minutes to study it. The students were then asked to verbally recite all of the words they could remember within three minutes. One week later, Dr. Crawford repeated the experiment with the same group and same list of words. However, on the second trial, students were given the sugar pill instead of the smart pill.
On the first trial, students from Group C recalled an average of seventeen words. On the second trial, students recalled an average of twenty words.
What should Dr. Crawford have done to improve the experiment?
By using the same list, Dr. Crawford is not giving students new material to memorize. Students may still remember the words on the list from the previous trial, possibly compromising results. Using a new list would test students’ ability to remember forty new words within five minutes during both trials.
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After much success with her initial experiments (i.e. Groups A and B) and pilot test, Dr. Crawford wanted to further test the effects of a “smart pill." She recruited a new group of twenty students, Group C, for this next experiment. In the first trial, she gave the students the smart pill, and then waited five minutes to give them the list of forty words. Students were instructed to memorize the list in any order and were given five minutes to study it. The students were then asked to verbally recite all of the words they could remember within three minutes. One week later, Dr. Crawford repeated the experiment with the same group and same list of words. However, on the second trial, students were given the sugar pill instead of the smart pill.
On the first trial, students from Group C recalled an average of seventeen words. On the second trial, students recalled an average of twenty words.
The students’ improved recall on the second trial is likely due to which of the following?
During the second trial, students in Group C were given the sugar pill instead of the smart pill. It is highly unlikely that the sugar pill improved memory, so we must search for what else may be causing this improvement. The students had previous exposure to the list of 40 words from the first trial. This may have made it easier for them to memorize a second time.
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A researcher is interested in studying the cognitive development of children. She administers an appropriate instrument to three groups of children at a school: 8-year olds, 9-year olds, and 10-year olds. She tests the students only once. This study is an example of a __________.
Cross-sectional studies involve measuring a particular construct at a given moment in time (a single cross-section of time). In cross-sectional studies, the researcher only measures once. In longitudinal studies, a group of individuals is studied across time (multiple cross-sections of time); for example, following a group of 9-year olds for 3 years. Sequential cohort studies blend cross sectional and longitudinal studies because you follow multiple cohorts at multiple times. For example, if the researcher wanted to make this study a sequential cohort design, she could re-measure the construct at different time periods. Finally, a case study is a detailed account of one individual (rather than a group) over a time period.
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What is the difference between reliability and validity?
A reliable measure consistently produces similar answers, and a valid measure produces correct or accurate answers. Imagine a soccer player shooting on an empty goal. If the player consistently misses to the left of the goal, their shooting is reliable, because they continue to miss in the same place, but not valid, because they are not scoring goals. If, on the other hand, the player scores on most of their shots, but scores all over the goal, they are valid, because they continually hit the intended target, but not reliable, because they do not score in the same place. If the player were to score in the same place on the goal over and over, they would be both consistent AND reliable. Veracity, or truthfulness, does not factor into reliability and validity.
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Which of the following is not a common difficulty associated with the double-blind study protocol?
In a double-blind protocol, both the research participants and the researchers engaging in the study are unaware of which participants are in the control group and which are in the experimental group. This actually makes subsequent meta-analysis of the double-blinded results easier, as a correctly applied double-blindness will remove any of the researcher's biases from the results.
Compare your answer with the correct one above
Melanie is a regular customer at a gun range, where she shoots paper targets with three different types of guns: a rifle, a pistol, and a shotgun. When firing the rifle, Melanie notices that her shots nearly always hit the target, but are evenly spread out throughout the paper's surface. When firing the pistol, Melanie's shots are all grouped within a few inches of each other, with the group overlaying the bull’s-eye on the target. When firing the shotgun, Melanie's shots are also tightly grouped, but the groups of shots are all slightly above the bull’s-eye. Which of the following terms is best describes Melanie's performance with the shotgun compared to her performance with the pistol?
Reliability is the ability of a measure, test, or effect to produce the same result upon repeated trials. In this case reliability was analogous to the grouping of shots on the target irrespective of the placement of the group. Validity is the ability of a test to measure what it is intended to measure or of a treatment to produce the effect it is purported to produce. In this case validity was analogous to the placement of shots on the target—the closer to the bull’s-eye, the more valid the shots.
In the scenario, the shots from the pistol—which hit both the target on the bull’s-eye and were grouped closely together—are valid and reliable. On the other hand, the shotgun shots—which are only grouped together but are not accurate to the bull’s-eye—are equally reliable but less valid.
Compare your answer with the correct one above
A sample of players on a baseball team are chosen to be drug tested. Which of the following methods could league officials use to ensure that the players are randomly selected?
Random selection allows all of the players on the team to have an equal chance of being chosen for testing. Choosing to test only players of a certain age or position, or only testing those that volunteer or have reached a certain statistical benchmark, would exclude a number of the players on the roster from having a chance to be chosen.
Compare your answer with the correct one above
Dana is participating in a study that asks her to press a red button every time the computer screen in front of her shows a letter X.
The computer screen shows a letter "T." Dana presses the red button. Dana's response is considered to be which of the following?
A false alarm is a response that says the target stimulus (in this case, the letter X) has been detected when that stimulus is not present.
Compare your answer with the correct one above
Dr. Crawford believes she has invented a pill to help with student memorization. For a trial experiment, she gathered two groups of twenty students. She gave the twenty students in Group A the “smart pill”, and the twenty students in Group B a sugar pill. After waiting five minutes, both groups of students were given a list of forty words, and were instructed to memorize the entire list in any order. The students were given five minutes to memorize the list. The students were then asked to verbally recite all of the words they could remember in any order within three minutes.
Group A recited an average of fifteen words, while Group B recited an average of ten words.
In this experiment, what is the independent variable?
The independent variable is what the researcher manipulates in order to test his or her hypothesis. In this experiment, Dr. Smart gave one group the smart pill and the other group a sugar pill in order to evaluate the smart pill's effect on student memorization.
Compare your answer with the correct one above