a. Calculate the estimate of the total profit using Ŷ. b. Is this an unbiased estimator for the total profit? Explain. c. Derive an expression for the variance of this estimator (Ŷ), and calculate the sample standard error. d. Another estimator for the total profit of the 50 companies is Ŷ* = Y₁ + N₂Ŷ₂, and from the sample i) Calculate the estimate of the total profit using Ŷ*. ii) Is this an unbiased estimator for the total profit? Explain. iii) Derive an expression for the variance of this estimator, and calculate the sample standard error.

How do I interpret the 6 characteristics whith the data given?   Column Mean Median Range Variance Std. dev. 1 - Cholesterol 253.92857 268 218 2276.291 47.710492

What is the slope of the median median line for the dataset in this table?

Two companies produce widgets of varying quality. An important measure of quality is the number of days the widgets can go before they need to be replaced. Do the following data provide evidence that the quality of widgets from the two companies differ? Round the p-value to three decimal places. Do not assume equal variances.   Widget Life in Days from Company 1 Widget Life in Days from Company 2 12.0 52.2 14.0 45.8 48.4 44.6 47.0 57.5 50.4 44.2 57.4 50.8 30.8   43.0   30.0

3. Complete the first 3 columns of the table below. Values Deviations Square deviations X X - X (X-X)² Standard (z) scores X-X Z = a. Compute the sample variance and sample standard deviation by definition. b. Fill in the last column of the table c. Compute the coefficient of variation.

The role of the covariate is to:     a.Compare variables of interest without a nuisance variable masking true differences. b.Reduce within-wroup error variance and help eliminate confounding variable bias. c.To determine the predictive power of the independent variable using odds d.A & B