Suppose you are interested in understanding the causal impact of having an MBA (versus just an undergraduate degree in business) on earnings.  To this end, you estimate a regression of the following form:

EARNINGS = 55679 + 27809(MBA)

The estimated coefficient above suggests that individuals with an MBA earn $27,809 more than those with just a business undergraduate, on average.  Give an example of how omitted variable bias might impact this estimate

You pick two cards, with replacement, from a standard 52 card deck. The probability that both are red 7's is approximately:

Question options:

Allen's hummingbird (Selasphorus sasin) has been studied by zoologist Bill Alther.† Suppose a small group of 20 Allen's hummingbirds has been under study in Arizona. The average weight for these birds is x = 3.15 grams. Based on previous studies, we can assume that the weights of Allen's hummingbirds have a normal distribution, with σ = 0.22 gram. (a) Find an 80% confidence interval for the average weights of Allen's hummingbirds in the study region. What is the margin of error? (Round your answers to two decimal places.) (b) What conditions are necessary for your calculations? (Select all that apply.) -n is large -σ is known -σ is unknown -normal distribution of weights -uniform distribution of weights (c) Interpret your results in the context of this problem. -The probability to the true average weight of Allen's hummingbirds is equal to the sample mean. -There is a 20% chance that the interval is one of the intervals containing the true average weight of Allen's hummingbirds in this region. -There is an 80% chance that the interval is one of the intervals containing the true average weight of Allen's hummingbirds in this region. -The probability that this interval contains the true average weight of Allen's hummingbirds is 0.20. -The probability that this interval contains the true average weight of Allen's hummingbirds is 0.80. (d) Find the sample size necessary for an 80% confidence level with a maximal margin of error E = 0.15 for the mean weights of the hummingbirds. (Round up to the nearest whole number.) ______ hummingbirds

Let X and Y denote the tarsus lengths of female and
male grackles, respectively. Assume normal distributions for X and Y. Independent samples are selected from these populations and suppose

Test at 5% significance level whether the true mean tarsus length of female grackles is smaller than that of male grackles. What is the rejection region for this test?

A researcher has a strange habit to use a sample size between √? 3(Cube root of N) and √? 2(Square root of N) , where ? is the size of the population that she investigates. Under what circumstances, do you suggest her to use a correction factor for the variance of the sampling distribution while estimating a confidence interval for the population mean? What if she does not take your suggestion seriously? Describe the potential problems involved.

If s 2/1 represents the larger of two sample variances, can the F test statistic ever be less than 1?

can the F test statistic ever be a negative number?

Is the f distribution symmetric, skewed left or skewed right?

Suppose that there are 8 blue credit cards, 6 red credit cards and 4 blue debit cards in a box. It is known that color and card type are to be independent when a card is selected at random from this box. a) How many red debit cards must be present? b) Suppose that, 6 cards are randomly selected in a row with replacement. What is the probability that 2 blue credit cards and 2 blue debit cards are selected? c) Suppose that, 6 cards are randomly selected in a row without replacement. What is the probability that 2 blue credit cards and 2 blue debit cards are selected?

Assume that random guesses are made for seven multiple choice questions on an SAT​ test, so that there are

equals ​trials, each with probability of success​ (correct) given by

p =0.45

.

Find the indicated probability for the number of correct answers.

Find the probability that the number x of correct answers is fewer than

4

.

1. For the following problems, construct a scatter plot using excel. After the plot is drawn, analyze it to determine which type of relationship, if any, exists.

Enter data in the excel worksheet (let’s say in column A you enter x data, in B you enter y data)à Select Data --> CLICK Insert --> Click Scatter --> Click the first case that contains unconnected points -->release the mouse                                    

If you choose layout 9, you get the regression equation that can give you more detailed information

b.   For each of the following problems compute the correlation coefficient r, r², (show the intermediary steps) and summarize/explain the results

PROBLEM 2

The data below shows the score on a promotion test given to police officers and the number of hours studied.

PROBLEM 3: An emergency service wishes to see whether there a relationship exists between the outside temperature and the number of emergency calls it receives. The data is shown below.

Temperature x     |      68        74        82        88        93        99        101

Number of calls   |      3          4          7          8          9          12        13

Assume that a standard deck of 52 playing cards is randomly shuffled (13 cards of 4 types of suits - clubs, diamonds, hearts, and spades). If Alex draws a card from it 4 times with replacement, how many different combinations of suits can he get? (Suppose we further assume that the order doesn't matter: (clubs, diamonds, hearts, hearts) is equal to (hearts, clubs, diamonds, hearts). However, (clubs, diamonds, hearts, hearts) is different with (hearts, clubs, clubs, hearts).)

Question 1: Table 1 shows the number of customers visited by a salesman over an 80-week period. Table 1: Customers Visited Over an 80-Week Period 68 64 75 82 68 60 62 88 76 93 73 79 88 73 60 93 71 59 85 75 61 65 75 87 74 62 95 78 63 72 66 78 82 75 94 77 69 74 68 60 96 78 89 61 75 95 60 79 83 71 79 62 67 97 78 85 76 65 71 75 65 80 73 57 88 78 62 76 53 74 86 67 73 81 72 63 76 75 85 77

a) Determine the mean, mode(s) and median.

In studies for a medication, 6% of patients gained weight as a side effect. Suppose 703 patients are randomly selected. Use the normal approximation to the binomial to approximate the probability that:

A. Exactly 43 patients will gain weight as a side effect

B. No more than 43 patients will gain weight as a side effect

C. At least 57 patients will gain weight as a side effect. What does this result suggest?

1. Please show how to do in Excel
2. Using Log-log model to estimate the demand function

• Model: log(sales) = a + b * log(price) + error
• Explain the results in term of how price affects sales.

Question 1: Table 1 shows the number of customers visited by a salesman over an 80-week period. Table 1: Customers Visited Over an 80-Week Period 68 64 75 82 68 60 62 88 76 93 73 79 88 73 60 93 71 59 85 75 61 65 75 87 74 62 95 78 63 72 66 78 82 75 94 77 69 74 68 60 96 78 89 61 75 95 60 79 83 71 79 62 67 97 78 85 76 65 71 75 65 80 73 57 88 78 62 76 53 74 86 67 73 81 72 63 76 75 85 77

b) Determine the values for the first and third quartiles (Q1 and Q3).