Which of the following statements about two-sample inference procedures are true? There may be more than one correct statement; check all that are true. Question options: a) If the population variances are known to be equal, then the pooled-variance t procedure is a better choice than the Welch procedure. b) The Welch t procedure and pooled-variance t procedure both assume the sample means are equal. c) The Welch t procedure and pooled-variance t procedure both require equal sample sizes. d) The pooled-variance t procedure only works if the sample size is very large.

The null hypothesis that there is no difference between the means of two independent populations is…

Answered: Which of the following statements about…

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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Wecan infer a statistically significant difference between two population meanswhen:a. ourestimates of the two means are different.b. thevariances of the two means do not overlap.c. thestandard deviations of the two means do not overlap.d. the95% confidence intervals for the two means do not overlap.e. the95% confidence intervals for the two means are of different widths.
B. A sample data has a distribution that has a single mode and is strongly positively skewed. An analyst computes three measures of location for this data; the mean, the median and mode. (i) State the largest of these three location measures. (ii) Suggest, with a reason, which would be the best measure of location.
An educator wants to construct a 99% confidence interval for the proportion of elementary school children in Michigan who are proficient in reading. Estimate the sample size needed to conduct this survey and assume that there there is no information available to be used from a previous study. Use a margin of error of 3%. What is the sample size: _________
I am to do a project for an inferential statistics class and I would like some basic guidance. I am to propose a research question. My proposed research question is "Does drinking stimulants such as coffee improve a student's grades?" It was suggested to me that my population could be the students at my school. I will impliment simple random sampling by devising two groups of students, one being a group who often consume stimulants like coffee and another who seldomly or never consume a stimulant such as coffee. Upon gathering the data of each group I will need to compare the average grades for each group using independent samples t-test for both respective groups. My Hypothesis test will be a two independent samples test for mean. My question is what are the limitations? (How could bias and/or confounding variables could limit this study?) Also what graph do you think would be best served to visually display the data?
In addition to equal variances, what other assumption is necessary in (a)? A. In addition to equal variances, it must be assumed that the population sizes are equal. B. In addition to equal variances, no other assumptions must be made because the sample sizes are large enough (greater than or equals 30 for each sample). C. In addition to equal variances, it must be assumed that the samples are specifically chosen and not independently sampled. D. In addition to equal variances, it must be assumed that the sample means are equal.
The accuracy of a census report on a city in southern California was questioned by some government officials. A random sample of 1215 people living in the city was used to check the report, and the results are shown below. Ethnic Origin Census Percent Sample Result Black 10% 126 Asian 3% 31 Anglo 38% 463 Latino/Latina 41% 525 Native American 6% 58 All others 2% 12 Using a 1% level of significance, test the claim that the census distribution and the sample distribution agree.
1. We want to investigate whether traffic accidents are more likely on certain days of the week on certain road sections. Which of the following tests best fits the situation?Choose one:a. Two-way analysis of variance OR b. Compatibility test OR c. Paired t-test 2. In which of the following can it be assumed that the sample comes from a normal distribution?Choose one:a. In the Runs test (random test)b. In the compatibility testc. In a two-way analysis of variance
As such, the final conclusion is that... There is sufficient evidence to warrant rejection of the claim that the first population mean is less than the second population mean. There is not sufficient evidence to warrant rejection of the claim that the first population mean is less than the second population mean. The sample data support the claim that the first population mean is less than the second population mean. There is not sufficient sample evidence to support the claim that the first population mean is less than the second population mean.
A popular theory is that presidential candidates have an advantage if they are taller than their main opponents. Listed are heights (in centimeters) of randomly selected presidents along with the heights of their main opponents. Complete parts (a) and (b) below. Height (cm) of President Height (cm) of Main Opponent 178 181 171 167 183 177 184 170 178 174 203 166 9 a. Use the sample data with a 0.05 significance level to test the claim that for the population of heights for presidents and their main opponents, the differences have a mean greater than 0 cm. In this example, Ha is the mean value of the differences d for the population of all pairs of data, where each individual difference d is defined as the president's height minus their main opponent's height. What are the null and alternative hypotheses for the hypothesis test? Họ: Ha cm H1: Hd cm (Type integers or decimals. Do not round.)
The accuracy of a census report on a city in southern California was questioned by some government officials. A random sample of 1215 people living in the city was sued to check the report, and the results are shown here: Ethnic Origin Census Percentage Sample Result Black 10% 127 Asian 3% 40 Anglo 38% 480 Latino/Latina 41% 502 Native American 6% 56 All Others 2% 10 Using a 1% level of significance, test the claim that the census distribution and the sample distribution agree.
You wish to test the following claim (H) at a significance level of a = 0.10. Ho: 1 = 2 Ha: 1 2 You believe both populations are normally distributed, but you do not know the standard deviations for either. However, DON'T assume that the variances of the two populations are equal. You obtain a sample of size n₁ = 14 with a mean of ₁ = 63.8 and a standard deviation of SD₁ = 14.8 from the first population. You obtain a sample of size n₂ = 26 with a mean of 2 = 58.6 and a standard deviation of SD2 = 9.2 from the second population. What is the test statistic for this sample? (Report answer accurate to three decimal places.) test statistic = What is the p-value for this sample? (Report answer accurate to four decimal places.) p-value= The p-value is... O less than (or equal to) a O greater than a This test statistic leads to a decision to... O reject the null O accept the null O fail to reject the null
Which of the following is not an assumption of the two-factor ANOVA? Group of answer choices a)The observations within each sample must be independent. b)The populations from which the samples are selected must be normal. c)The observations within each sample must have equal variances. d)The populations from which the samples are selected must have equal variances.

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