HW 01

#statistics

Class: STAT-211

Notes:

1.

These questions were stolen from later homework. We will learn how to answer the question given in the problem later. Identify the parameter being tested and the statistic that corresponds to it. (it will be a hypothesized parameter, meaning we are testing if believe it is really the parameter. Do not include any units. Note the answer is only looking for a number - not words.)

a) A doctor believes that someone who smokes Marijuana will have a lower body temperature than the usual 98.6°. He samples 41 marijuana smokers for an average of 100° with a standard deviation of 3.8°. Using 𝛼=0.05 test whether this average is significantly lower than normal.

Parameter: 𝜇 = 98.6
Statistic: x = 100

450

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b) The USDA thinks that on average 114 feed deliveries are late each day. To see how close they are, the next 365 days are watched. The average is 123 late deliveries daily with a standard deviation of 28 deliveries. Test whether the USDA is right using 𝛼=0.05.

Parameter: 𝜇 = 114
Statistic: x = 123

c) A mad scientist declares that the average weight of a brain is not less than 1104 grams. Igor doesn't believe him, so he randomly selects 1665 brains and finds the average weight is 1193 grams with a standard deviation of 328 grams. Can he conclude with an 𝛼 of 0.11 that the scientist is wrong?

Parameter: 𝜇 = 1104
Statistic: x = 1193

d) I asked 982 random statistics students how many hours they spend on homework. I found an average of 7.5 hours with a standard deviation of 3.9 hours. According to the learning objectives, students taking a 4-credit class are expected to do 12 hours of homework per week on average. Do I have enough evidence to prove my students are spending less time on their homework than they are supposed to?

Parameter: 𝜇 = 12
Statistic: x = 7.5

2.

Refer to the previous question describing the study of 22,071 male physicians who were randomly assigned to take either an aspirin or a placebo every other day. Match each of the following terms to its correct description:

b. sample a. all US males aged 40 or older
a. population b. the 22,071 male physicians
c. subject c. a physician in the study

3.

Choose the correct answer for each of the following questions.

(a) Which of the following is an example of a qualitative (also called categorical) variable?

(b) Which of the following variables is discrete?

(c) Which of the following is a quantitative (also called numeric) variable for which math makes sense?

4.

List whether each is categorical or numerical.\

a) The length of the forearm from elbow to wrist (in centimeters).

b) Whether or not the person has ever been the victim of a crime.

c) Number of music CDs owned.

d) Feeling about own weight (overweight, about right, underweight).

5.

The management of the San Diego Union-Tribune newspaper wanted to understand the average salary level of its subscribers. 1,000 subscribers were randomly selected to be interviewed so that this information could be collected.

a) The sample is:

b) The population is:

6.

In ​ 2000, there were​ 7,867 cases of whooping cough in the​ U.S., while in ​ 2002, there were​ 9,771 cases, according to the CDC. What might be misleading about concluding from these data that more people were getting whooping cough in​ 2002?

7.

Choose the correct answer for each of the following questions.

a) Which of the following is an example of a qualitative or categorical variable?

b) Which of the following variables is discrete?

c) Which of the following is a quantitative or numeric variable?

8.

An ecologist was interested in how fish distribution (specifically, the ratio of catfish to other fish) in a lake changed over time. The current study of 1028 fish contained 523 catfish. The ecologist estimated that​ 50.9% of the fish in the lake were catfish.

Which of the following is (are) the variable(s) of interest in this study?

9.

Which of the following are examples of ordinal data?

10.

For each scenario say whether the numerical variable described is discrete or continuous.

Continuous Correct: Your answer is correct. Your age
Continuous Correct: Your answer is correct. The length of your femur bone
Discrete  Correct: Your answer is correct. The number hours you are enrolled this semester
Discrete   Correct: Your answer is correct. The deaths from airline crashes last year
Continuous Correct: Your answer is correct. The amount of blood in your body
Discrete  Correct: Your answer is correct. How many green checks you have on this homework assignment
Continuous Correct: Your answer is correct. Your blood pressure

The amount of money you have

11.

Choose the correct answer for each of the following questions.

(a) Which of the following is an example of a qualitative (also called categorical) variable?

(b) Which of the following variables is discrete?

(c) Which of the following is a quantitative (also called numeric) variable?

12.

The BBC reported that, on average, college students drink 33 ounces of alcohol per week. CNN picked up the story because in the US, the average is only 24 ounces per week. Assume we want to test if that average is different for TAMU students, so we hire surveyors from all over the state of Texas, and they randomly select 100 students from the athletics department at A&M. They find the average is 16 ounces per week.

What is the population for which these results are valid?