**Multiple Choice Question**As mentioned earlier, in the presence of changing variability, the OLS estimators are unbiased, but their estimated standard errors are inappropriate. Since the t and the F tests are no longer valid, which are suggested strategies to correct the standard errors?- ○ White's robust standard errors- ○ The t and the F tests *are* valid.- ○ Luckily, the current version of Excel includes a correction for the standard errors.- ○ There are several methods proposed by Hachimoto to correct standard errors.

In OLS when the variance of errors are no longer constants that situation is called…

Answered: As mentioned earlier, in the presence…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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An ecologist is studying the impact of local polluted waters on the growth of alligators. The length of adult male alligators typically follows a normal distribution with a standard deviation of 2 feet. The ecologist wants to estimate the mean length of this population of alligators. Suppose she samples n alligators at random and uses the sample mean, X to as an estimator for u. a. What is the bias and variance of the estimator? (Note, these may be a function of n.) b. If n = 4, what is the probability that the estimator is within one foot of the true mean? (I.e. find P(|X – µ| < 1). c. What sample size, n, is required for the estimator to be within one foot of the true mean with 95% probability? (I.e. find the value of n that satisfies P(|X – µ| < 1) = 0.95.) d. Suppose the ecologist ends up sampling n = 9 alligators and calculates a sample mean of ī = 10.4 feet. Construct a 95% confidence interval for the population mean. e. Give an interpretation for the interval obtained in (d).
Listed below are the amounts of net worth (in millions of dollars) of the ten wealthiest celebrities in a country. Construct a 95% confidence interval. What does the result tell us about the population of all celebrities? Do the data appear to be from a normally distributed population as required? 257 215 198 175 159 153 153 153 150 148 What is the confidence interval estimate of the population mean µ? million < µ<$ million (Round to one decimal place as needed.)
A2
Below indicate whether the appropriate test would be an independent t-test, dependent t-test, One-way ANOVA, or z-test. . A statistics professor wants to know if students who turn their homework in on time get higher exam grades than students who do not turn their homework in on time.
Under the logic of the hypothesis test of ANOVA, the F-statistic is made up of the ratio of Mean Squares between over Mean Squares within: F = MS Between MSwithin If the variance observed in an ANOVA relationship does not have enough of an MS Between effect There is too much noise in your system, and you should try your experiment again to confirm the findings. The F-ratio will approach 1 in the long run, since there is no MS Between effect. The F-ratio will become relatively large, since there is more variance to work with. O The F-ratio will approach 0 in the long run, since the MS Within will cancel out the effect.
Consider the trash bag problem. Suppose that an independent laboratory has tested trash bags and has found that no 30-gallon bags that are currently on the market have a mean breaking strength of 50 pounds or more. On the basis of these results, the producer of the new, improved trash bag feels sure that its 30-gallon bag will be the strongest such bag on the market if the new trash bag's mean breaking strength can be shown to be at least 50 pounds. The mean of the sample of 39 trash bag breaking strengths in Table 1.10 is x = 50.573. If we let u denote the mean of the breaking strengths of all possible trash bags of the new type and assume that o equals 1.61: Using the 95 percent confidence interval, can we be 95 percent confident that u is at least 50 pounds?
which of the following excel functions would you use to answer this question "Is the number if applications accepted for public colleges/universities the same as for private colleges/universities?" Options: 1) t-test: paired two sample for means 2) t-test: two sample assuming equal variances 3) t-test: two sample assumung unequal variances 4) z-test: two sample for means
A manufacturer must test that his bolts are 4.00 cm long when they come off the assembly line. He must recalibrate his machines if the bolts are too long or too short. After sampling 121 randomly selected bolts off the assembly line, he calculates the sample mean to be 4.21 cm. He knows that the population standard deviation is 0.83 cm. Assuming a level of significance of 0.02, is there sufficient evidence to show that the manufacturer needs to recalibrate the machines? Step 3 of 3: Draw a conclusion and interpret the decision.
This research was conducted with Korean adolescents in the Los Angeles area. Would you be willing to generalize the results of this study to Korean adolescents who live in other regions of the country? Why or why not.
The data from an independent-measures research study produce a sample mean difference of 4 points, and each sample has a variance of 10. If there are n = 20 scores in each sample, then what is the estimated standard error of the difference between means?
suppose that we have disjoint normal populations A and B and we want to find the standard error estimate for estimating the difference in their means. We have an IRS from A of size 8 with variance 25 and an IRS from B of size 9 with variance 16. What is the resulting standard error estimate if we assume both populations have the same population variance?
Show the 4-Step Method in testing significance of mean difference in the following case:A topic of recent clinical interest is the effect of different contraceptive methods on fertility. Suppose we wish to compare how long it takes users of either oral contraceptives (OCs) or diaphragms to become pregnant after stopping contraception. A study group of 20 OC users is formed, and diaphragm users who match each OC user with regard to age (within 5 years), race, parity (number of previous pregnancies), and socioeconomic status (SES) are found. The investigators compute the differences in time to fertility between previous OC and diaphragm users and find that the mean difference đ (OC minus diaphragm) in time to fertility is 4 months with a standard deviation (sd) of 8 months. Can we conclude that previous OC users take a significantly longer time to become pregnant than do previous diaphragm users?

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