Define what an endogenous variable is, describe three scenarios that may cause a problem of endogeneity, and what are minimal assumptions needed for a good instrument.

Why is the concept of variability important?

Aspirin III: Decision and Conclusion Regarding the experiment in the data frame Aspirin from the abd package, the researchers wanted to know whether or not taking aspirin affects one's risk of developing cancer. Recall that they defined their parameters as follows: p1 = the proportion of ALL individuals who would develop cancer, if all of them were to take aspirin like the subjects in the Aspirin group did. p2 = the proportion of ALL individuals who would develop cancer, if all of them were to take a placebo, like the subjects in the placebo group did. They ran the code for a two-sided significance test and got the following results: ## ## ## Inferential Procedures for the Difference of Two Proportions p1-p2:##   cancer grouped by treatment ## ## ## Descriptive Results:## ##          yes     n estimated.prop## Aspirin 1438 19934        0.07214## Placebo 1427 19942        0.07156## ## ## Inferential Results:## ## Estimate of p1-p2:    0.0005805 ## SE(p1.hat - p2.hat):  0.002586 ## ##…

7:08 iTECH Part V ork.potsdam.edu Part VI © 4G37% 5 What graphical display is appropriate for comparing the distribution of patient death rates between hospitals that use computer systems and those that rely on the âlpaperâ system? A. A scatterplot. B. A bar chart. C. A stem-and-leaf display. D. Side-by-side boxplots. 4 Mr. Prudence read about the study results and concluded from there that hospitals should adopt computerized automation of notes and records because it increases patientsâ chance of survival. Which of the following is a correct statement about Mr. Prudenceâs conclusion? A. It is a valid conclusion because the study was based on a very large number of patients. B. It is a valid conclusion because the study results showed that hospitals which use computerized systems have a lower patient death rate. C. It is an invalid conclusion because this study does not necessarily prove a causal relationship between the use of ||| computerized system and hospital mortality. D. Both A)…

A statistical program is recommended. A company that sells musical instruments has been in business for five years. During that time, sales of pianos increased from 13 units in the first year to 77 units in the most recent year. The firm's owner wants to develop a forecast of piano sales for the coming year. The quarterly sales data follow. Year Quarter 1 Quarter 2 Quarter 3 Quarter 4 Total YearlySales 1 5 2 1 5 13 2 7 4 4 14 29 3 11 3 5 16 35 4 12 9 7 22 50 5 19 10 13 35 77 (a) Deseasonalize the data. (Round your answers to four decimal places.)   Year Quarter  Sales  Adjusted Deseasonalized   Seasonal Sales       Index       1 1  5 1.3407   1 2  2 0.5998   1 3  1 0.4842   1 4  5 1.5753   2 1  7 1.3407   2 2  4 0.5998   2 3  4 0.4842   2 4  14 1.5753   3 1  11 1.3407   3 2  3 0.5998   3 3  5 0.4842   3 4  16 1.5753   4 1  12 1.3407   4 2  9 0.5998   4 3  7 0.4842   4 4  22 1.5753   5 1  19 1.3407   5 2  10 0.5998   5 3…

A statistical program is recommended. A company that sells musical instruments has been in business for five years. During that time, sales of pianos increased from 13 units in the first year to 77 units in the most recent year. The firm's owner wants to develop a forecast of piano sales for the coming year. The quarterly sales data follow. Year Quarter 1 Quarter 2 Quarter 3 Quarter 4 Total YearlySales 1 5 2 1 5 13 2 6 4 4 14 28 3 11 3 5 16 35 4 12 9 7 22 50 5 19 10 13 35 77 (a) Use the following dummy variables to develop an estimated regression equation to account for any seasonal and linear trend effects in the data: x1 = 1 if quarter 1, 0 otherwise; x2 = 1 if quarter 2, 0 otherwise; and x3 = 1 if quarter 3, 0 otherwise. (Let t = 1 denote the time series value in quarter 1 of year 1; t = 2 denote the time series value in quarter 2 of year 1;    and t = 20 denote the time series value in quarter 4 of year 5. Round your numerical values to two decimal places.) t =…

I need the answer to this question, please? An article included a summary of findings regarding the use of SAT I scores, SAT II scores, and high school grade point average (GPA) to predict first-year college GPA. The article states that "among these, SAT II scores are the best predictor, explaining 17 percent of the variance in first-year college grades. GPA was second at 15.5 percent, and SAT I was last at 13.5 percent." If the data from this study were used to fit a least squares line with y = first-year college GPA and x = high school GPA, what would the value of r2 have been? r2 =

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7) A department store manager has monitored the number of complaints received per week about poor service. The probabilities for numbers of complaints in a week, established by this review, are shown in the table. Number of complaints    0    1    2    3    4    5Probability    0.18    0.26    0.35    0.09    0.07    0.05 What is the variance of complaints received per week? Please round your answer to the nearest hundredth.

When you do not have the luxury of centering the statistics, you may need to define a non-centrality parameter. How would you do this, and why? Provide an example, including detailed explanations, formulas, and necessary visuals.