Learn Comparing two groups with Plainmath's Expert Help and Detailed Explanations

Give a correct answer for this question In order to compare the relationship between two categorical variables, the best inference technique is ?

Inference about cause and effect but cant

Two different analytical methods were used to determine residual chlorine in sewage effluents. Both methods were used on the same samples, but each came from various locations, with differing amounts of contact time with the effluent. The concentration of Cl in mg//L was determined by the two methods, and the following results were obtained:
Method $A:0.39,0.84,1.76,3.35,4.69,7.70,10.52,10.92$
Method $B:0.36,1.35,2.56,3.92,5.35,8.33,10.70,10.91$
(a) What type of t test should be used to compare the two methods and why?
(b) Do the two methods give different results?
(c) Does the conclusion depend on whether the 90%, 95% or 99% confidence levels are used?

In $Z_{40}\oplus Z_{30}$ find two subgroups of order 12

Give the correct answer and solve given
a. Test for a difference in the means in the two populations using an $[\alpha =.05t-test.]$
b. Place a 95% confidence interval on the difference in the means of the two populations.
c. Compare the inferences obtained from the results from the Wilcoxon rank sum test and the -test.
d. Which inferences appear to be more valid, inferences on the means or the medians?

Give full and correct answer for this questions 1) A t-test is a ? 2) Which of the following statement is true? a)The less likely one is to commit a type I error, the more likely one is to commit a type II error, b) A type I error has occurred when a false null hypothesis has been wrongly accepted. c) A type I error has occurred when a two-tailed test has been performed instead of a one-tailed test, d) None of the above statements is true. 3)Regarding the Central Limit Theorem, which of the following statement is NOT true? a.The mean of the population of sample means taken from a population is equal to the mean of the original population. b. The frequency distribution of the population of sample means taken from a population that is not normally distributed will approach normality as the sample size increases. c. The standard deviation of the population of sample means is equal to the standard deviation of the, original population. d. The frequency distribution of the population of sample means taken from a population that is not normally distributed will show less dispersion as the sample size increases.

In a comparison between two. major brands of broiler chickens, 70 of 160 Perdue chickens in a SRS tested positive for food-borne illness bacteria. In a SRS of 160 Tyson chickens, 132 tested positive. Wed

The ANOVA technique is designed to evaluate the null hypothesis that: a) Two populations have equal variance b) The mean of each treatment group is no different from the mean of the pooled population c) The mean square error (MSE) of the treatment group is larger than the overall MSE Write down the sum of squares decomposition and explain, briefly, in your own words how the sum of squares decomposition is used to conduct statistical inference in ANOVA.

To explain: why the combination $(\genfrac{}{}{0ex}{}{n}{r})=(\genfrac{}{}{0ex}{}{n}{r,n-r})$

Is statistical inference intuitive to babies? In other words, are babies able to generalize from sample to population? In this study,1 8-month-old infants watched someone draw a sample of five balls from an opaque box. Each sample consisted of four balls of one color (red or white) and one ball of the other color. After observing the sample, the side of the box was lifted so the infants could see all of the balls inside (the population). Some boxes had an “expected” population, with balls in the same color proportions as the sample, while other boxes had an “unexpected” population, with balls in the opposite color proportion from the sample. Babies looked at the unexpected populations for an average of 9.9 seconds (\(sd = 4.5\) seconds) and the expected populations for an average of 7.5 seconds (\(sd = 4.2\) seconds). The sample size in each group was 20, and you may assume the data in each group are reasonably normally distributed. Is this convincing evidence that babies look longer at the unexpected population, suggesting that they make inferences about the population from the sample? Let group 1 and group 2 be the time spent looking at the unexpected and expected populations, respectively. A) Calculate the relevant sample statistic. Enter the exact answer. Sample statistic: _____

B) Calculate the t-statistic. Round your answer to two decimal places. t-statistic = ___________

C) Find the p-value. Round your answer to three decimal places. p-value =__________

True // False: comparing means. Determine if the following statements are true or false, and explain your reasoning for statements you identify as false.
(a) When comparing means of two samples where $n_1=20$
and $n_2=40$,
we can use the normal model for the difference in means since $n_2\ge 30.$
(b) As the degrees of freedom increases, the t-distribution approaches normality.
(c) We use a pooled standard error for calculating the standard error of the difference between means when sample sizes of groups are equal to each other.

Provide three examples of studies when we can use (a) the pooled, (b) non-pooled, and (3) paired inference to compare means of two populations.

Explain how its

In general, the t test for correlated groups is a more powerful test than the sign test. Is this statement true? Explain why? Can you think of situations in which the sign test might be more powerful than the t test for correlated groups (assume N is the same for both tests, etc.)?

Solve given Inferences involving two populations
A study in Pediatric Emergency Care compared the injury severity between younger and older children.
One measure reported was the Injury Severity Score(ISS).
The standard deviation of ISS scores for 37 children 8 years or younger was 23.9,v and the standard deviation for 36 children older than 8 years was 6.8. Assume that ISS scores are normally distributed for both age groups.
At the 0.01 level of significance, is there sufficient
Feason to conclude that the standard deviation of Iss
Scores for younger children is larger than the standard deviation of Iss scores for older children?

Ozone The Environmental Protection Agency is examin- ing the relationship between the ozone level (in parts per million) and the population (in millions) of U.S. cities.
Part of the regression analysis is shown.
Dependent variable is: Ozone
R-squared $=84.4\mathrm{\%}$
$s=5.454$ with $16-2=14$ df
Variable Coefficient SE(Coeff)
Intercept 18.892 2.395
Pop 6.650 1.910
a) We suspect that the greater the population of a city, the higher its ozone level. Is the relationship significant? Assuming the conditions for inference are satisfied, test an appropriate hypothesis and state your conclu- sion in context.
b) Do you think that the population of a city is a useful predictor of ozone level? Use the values of both R2 and s in your explanation.

Solve given Inferences involving two populations Inference about two Population Proportions:
Independent Samples:
A government housing agency is comparing home ownership rates among several immigrant groups. In a sample of 235 families who emigrated to the U.S. from Eastern Europe five years ago, 165 now own homes. In a sample of 195 families who emigrated to the U.S. from Pacific islands five years ago, 125 now own homes.

Calculate the period of prey and predator populations using the approximation if $T=7.25$

The university conducted a study to observe the efficiency of students to see whether students do better when they study all at once or in intervals.
One group of 12 participants participated in the survey after studying for one hour continuously.
The other group of 12 participated in the survey after studying for three twenty-minute sessions.
As per the survey, results group 1 had a mean score of 75 and a variance of 120.
Second group had a mean score of 86 and a variance of 100. Assuming the normal populations, independent samples, and equal population variances conditions hold, are the mean test scores of these two groups significantly different at the 0.05 level?

When should we use pooled, non-pooled or paired output to compare the means of two populations. you need to be specific and give the correct answer.