1.What type of distribution is this?
This is the marginal distribution of student level.
A conditional distribution turns each count in the table into a percent of individuals who fit a specific value of one of the variables.(means that in this case, the distribution of categories would be straight A, B+, B, etc...instead of straight A and Not Straight A)
A marginal distribution shows the totals (in counts or percents) for all the values of just one of the variables.(In this case, the categories straight A and Not Straight A are exactly marginal distribution because it only mentioned one term--straight A, and its goal is only to determine whether or not students are straight A instead of trying to know how many students are B+, etc...)
2.Based on these conditional distributions, what can we say about the association between student level and straight A status?
A.Graduate students were more likely to have straight A's than undergraduate students.
B.Straight A students were more likely to be graduate students than undergraduate students.
These two options(sentences) contain different subject, option A's subject is graduate student, while the subject of option B is straight A student. The subject of the sentence always determine which row or column we should look at. What we need to do, is to look at the row or column these to subjects are at. Let's look at option A, whose subject is graduate students. Since the term"graduate" is at column two, so this determine that we should look at column two. From column two, we can know that among 500 graduate student, 60 of them get straight A, which means the percentage of straight A students among graduate students is 12%. Option A's goal is to compare the number of graduate and undergraduate students who get straight A. Use the same method, we can know that the percentage of straight A students among undergraduate students is 6%. Therefore, the statement "Graduate students were more likely to have straight A's than undergraduate students."
Use the same method to deal with option B. Since the subject of it is straight A students, this directly determine that we need to look at row one. Among 300 students who got straight A, there are 60 graduate students and 240 undergraduate students, so it's clearly that Straight A students were more likely to be undergraduate students than graduate students, which means option B is false.
2016年10月23日星期日
Conditional distributions and relationships
EXAMPLE:
A small private college was curious about what levels of students were getting straight A grades. College officials collected data on the straight A status from the most recent semester for all of their undergraduate and graduate students. The data is shown in the two-way table below:
1.What type of distribution is this?
This is the marginal distribution of student level.
A conditional distribution turns each count in the table into a percent of individuals who fit a specific value of one of the variables.(means that in this case, the distribution of categories would be straight A, B+, B, etc...instead of straight A and Not Straight A)
A marginal distribution shows the totals (in counts or percents) for all the values of just one of the variables.(In this case, the categories straight A and Not Straight A are exactly marginal distribution because it only mentioned one term--straight A, and its goal is only to determine whether or not students are straight A instead of trying to know how many students are B+, etc...)
2.Based on these conditional distributions, what can we say about the association between student level and straight A status?
A.Graduate students were more likely to have straight A's than undergraduate students.
B.Straight A students were more likely to be graduate students than undergraduate students.
These two options(sentences) contain different subject, option A's subject is graduate student, while the subject of option B is straight A student. The subject of the sentence always determine which row or column we should look at. What we need to do, is to look at the row or column these to subjects are at. Let's look at option A, whose subject is graduate students. Since the term"graduate" is at column two, so this determine that we should look at column two. From column two, we can know that among 500 graduate student, 60 of them get straight A, which means the percentage of straight A students among graduate students is 12%. Option A's goal is to compare the number of graduate and undergraduate students who get straight A. Use the same method, we can know that the percentage of straight A students among undergraduate students is 6%. Therefore, the statement "Graduate students were more likely to have straight A's than undergraduate students."
Use the same method to deal with option B. Since the subject of it is straight A students, this directly determine that we need to look at row one. Among 300 students who got straight A, there are 60 graduate students and 240 undergraduate students, so it's clearly that Straight A students were more likely to be undergraduate students than graduate students, which means option B is false.
1.What type of distribution is this?
This is the marginal distribution of student level.
A conditional distribution turns each count in the table into a percent of individuals who fit a specific value of one of the variables.(means that in this case, the distribution of categories would be straight A, B+, B, etc...instead of straight A and Not Straight A)
A marginal distribution shows the totals (in counts or percents) for all the values of just one of the variables.(In this case, the categories straight A and Not Straight A are exactly marginal distribution because it only mentioned one term--straight A, and its goal is only to determine whether or not students are straight A instead of trying to know how many students are B+, etc...)
2.Based on these conditional distributions, what can we say about the association between student level and straight A status?
A.Graduate students were more likely to have straight A's than undergraduate students.
B.Straight A students were more likely to be graduate students than undergraduate students.
These two options(sentences) contain different subject, option A's subject is graduate student, while the subject of option B is straight A student. The subject of the sentence always determine which row or column we should look at. What we need to do, is to look at the row or column these to subjects are at. Let's look at option A, whose subject is graduate students. Since the term"graduate" is at column two, so this determine that we should look at column two. From column two, we can know that among 500 graduate student, 60 of them get straight A, which means the percentage of straight A students among graduate students is 12%. Option A's goal is to compare the number of graduate and undergraduate students who get straight A. Use the same method, we can know that the percentage of straight A students among undergraduate students is 6%. Therefore, the statement "Graduate students were more likely to have straight A's than undergraduate students."
Use the same method to deal with option B. Since the subject of it is straight A students, this directly determine that we need to look at row one. Among 300 students who got straight A, there are 60 graduate students and 240 undergraduate students, so it's clearly that Straight A students were more likely to be undergraduate students than graduate students, which means option B is false.
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