Two samples, each with n = 10 participants, have a pooled variance, sp2 = 180. What is the estimated standard error, s(M1-M2) for the sample mean difference in the t-test for independent samples?

Seven acute schizophrenics and 10 chronic schizophrenics have been measured on a clarity of thinking scale. The mean for the acute sample was 52, with s = 12, and the mean for the chronic sample was 44, with s = 11. Perform a pooled-variance t test with alpha = .05 (two-tailed), and state your statistical conclusion.

A study has been made to compare the nicotine contents of two brands of cigarettes. Ten cigarettes of Brand A had an average nicotine content of 4.3 milligrams with a standard deviation of 0.6 milligram. Eight cigarettes of Brand B had an average nicotine content of 3 milligrams with a standard deviation of 0.4 milligram. Assume that the two sets of data are independent random samples from normal populations with equal variances. Answer the following, and round off your answer to three decimal places. (a) Find a pooled estimate of the population standard deviation. (b) Construct a 95% confidence interval for the difference between the mean nicotine contents of the two brands of cigarettes. (☐☐)

A social psychologist is interested in knowing whether people are more aggressive if they are in the presence of a weapon, such as a gun Treatment Condition- T1, as compared to when they are in a room with an innocuous item such as a tennis racket Control Condition-T2. The study used one sample of 17 college students and had all of the students in the sample participate in both treatment conditions. The mean of the difference scores was 18.0 and the variance (s2) was 612. An alpha level of .01 was set. Calculate the t. A  3.000 B  2.780 C  2.152 D  1.765

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?

A researcher is interested whether a new drug is effective in changing patients' cholesterol levels. She divided 33 patients into 3 groups according to the dosage the patient received. The cholesterol levels of all patients are measured and used as the data for the Analysis of Variance (ANOVA). If she reported the test statistic F = 2.1 What is the degree of freedom for the numerator of the F statistic? What is the degree of freedom for the denominator of the F statistic? What is the P-value of the F-test? (Round to 3 decimals) Given the significance level of 0.01, what can she conclude from the test? *The patients in differnt groups have simliar average cholesterial levels. The drug made no difference. *At least one group of patients have an average cholesterol level that is different from the other groups. The drug may have an effect.

A researcher decides to measure anxiety in group of bullies and a group of bystanders using a 23-item, 3 point anxiety scale.  Assume scores on the anxiety scales are normally distributed and the variance among the group of bullies and bystanders are the same. A group of 30 bullies scores an average of 21.5 with a sample standard deviation of 10 on the anxiety scale.  A group of 27 bystanders scored an average of 25.8 with a sample standard deviation of 8 on the anxiety scale. You do not have any presupposed assumptions whether bullies or bystanders will be more anxious so you formulate the null and alternative hypothesis based on that.

A sample with SS=30 and a variance of s2 =10 has n=4 scores. True or False?

An independent measures design study with n= 16 in each sample produces a sample meam difference of 4 points and a pooled variance of 24. Wht is the value of t statistic?

Suppose a researcher pbserves a population of 12 people and computes SS=204. What is the variance? What is the standard deviation?