Homework 4

In a box, there are 8 red, 7 blue and 6 green balls. One ball is picked up randomly. What is the probability that it is neither red nor green?

1/3

In your new role as a data analyst for a large hospital chain, the CEO has asked you to explore patient outcomes at a newly built hospital ("Mountain View") versus an existing hospital ("Greenside"). She is specifically interested in seeing whether patients who are seen for heart attacks are being readmitted to the hospital more often in the new facility. You looked at data from a random sample of visits to the two hospitals during the last year. Was Patient Readmitted to the Hospital within 30-days following treatment for heart attack? Hospital Site Visited Mountain View Greenside Total Yes 54 16 70 No 705 171 876 Total 759 187 946 If you choose a person from the survey at random, what is the probability that the person had visited the Greenside hospital and was not readmitted to the hospital within 30-days following treatment for heart attack?

18.08%

A group of 262 students was polled to determine whether they exercise regularly (engaging in moderate activity for 30-60 min, 3 or more times per week). Exercises Regularly Gender Female Male Total No 72 96 168 Yes 58 36 94 Total 130 132 262 If you choose a person from the survey at random, what is the probability that the person is a male AND does not exercise regularly?

36.64%

A group of 262 students was polled to determine whether they exercise regularly (engaging in moderate activity for 30-60 min, 3 or more times per week). Exercises Regularly Gender Female Male Total No 72 96 168 Yes 58 36 94 Total 130 132 262 If you choose a person from the survey at random, what is the probability that the person is male?

50.38%

A group of 262 students was polled to determine whether they exercise regularly (engaging in moderate activity for 30-60 min, 3 or more times per week). Exercises Regularly Gender Female Male Total No 72 96 168 Yes 58 36 94 Total 130 132 262 If you choose a person from the survey at random, given that the person does not exercise regularly, what is the probability that the person is a male?

57.14%

A group of 262 students was polled to determine whether they exercise regularly (engaging in moderate activity for 30-60 min, 3 or more times per week). Exercises Regularly Gender Female Male Total No 72 96 168 Yes 58 36 94 Total 130 132 262 If you choose a person from the survey at random, what is the probability that the person does not exercise regularly?

64.12%

Players using cleats Player performance in soccer games Scored a goal Did not score a goal Total Yes 31 11 42 No 16 9 25 Total 47 20 67 Given that a player was wearing cleats, what is the probability they scored a goal?

73.81%

In your new role as a data analyst for a large hospital chain, the CEO has asked you to explore patient outcomes at a newly built hospital ("Mountain View") versus an existing hospital ("Greenside"). She is specifically interested in seeing whether patients who are seen for heart attacks are being readmitted to the hospital more often in the new facility. You looked at data from a random sample of visits to the two hospitals during the last year. Was Patient Readmitted to the Hospital within 30-days following treatment for heart attack? Hospital Site Visited Mountain View Greenside Total Yes 54 16 70 No 705 171 876 Total 759 187 946 If you choose a person from the survey at random, what is the probability that the person visited the new Mountain View hospital site?

80.23%

Researchers administer an IQ test to a group of high school students. They then correlate the scores on the IQ test with the student's current high school GPA. This is an example of what type of validity?

Concurrent validity

Reliability is concerned with:

Consistency

Researchers want to determine the percentage of students who own iPhones and Android cell phones. They go to a popular spot on campus and ask first 100 students who pass what type of cell phone they own. What type of sampling method is this?

Convenience

Which of the following is concerned with monitoring estimates of present performance and predictions of future performance?

Criterion validity

In your new role as a data analyst for a large hospital chain, the CEO has asked you to explore patient outcomes at a newly built hospital ("Mountain View") versus an existing hospital ("Greenside"). She is specifically interested in seeing whether patients who are seen for heart attacks are being readmitted to the hospital more often in the new facility. You looked at data from a random sample of visits to the two hospitals during the last year. Was Patient Readmitted to the Hospital within 30-days following treatment for heart attack? Hospital Site Visited Mountain View Greenside Total Yes 54 16 70 No 705 171 876 Total 759 187 946 True or false: The "readmission rate" (the percentage of patients readmitted to the hospital within 30-days following treatment for heart attack) was greater at Mountain View than at Greenside

False

True or False, the probability of an outcome can be a negative number.

False

High school class rank is highly correlated with college GPA. This is an example of what type of validity?

Predictive validity

A researcher knows that there are more seniors at their university than freshman. They have the follwing data about the population: 19.10%Freshman22.19%Sophomore25.66%Junior32.28%Senior0.78%Non-degree They want their sample to represent the distribution of class ranks and they want to ensure non-degree seeking students are also a representative part of their sample. What type of sample do they want?

Stratified random

If a measure is consistent over multiple occasions, what type of reliabiility does the test have?

Test-retest reliability

Which of the following statements is/are TRUE about convenience samples (choose one or more):

They are biased and nonrepresentative of the population, They are cheaper and more time efficient than other sampling methods

A neighborhood with 1000 houses is organized on a grid with 10 houses per block. If the house on the NE corner of each block are sampled (for a total of 100 households) - what sort of sample is this?

systematic

Samples should be ___________________ (choose one or more) when considering the population from which they were drawn.

unbiased, representative