Some researchers claim that herbal supplements improve human memory. To test this claim, a researcher selects a sample of n = 25 college students. Each student is given herbal supplements daily for 6 weeks and then all the participants are given a standardized memory test. For the population, scores on the tests are normally distributed with µ = 70 and σ= 20. The sample of n = 25 students had a mean score of M = 80. Can we conclude that the memory scores of the sample after the  “herbal supplement” treatment are significantly greater than those of the general population(population mean before treatment)? Perform a hypothesis test using  a z- score statistic. Use a one-tailed test with α = .05. a. You will be using the z-score statistic instead of the t test to test the hypotheses because b. The alternative hypothesis in symbols is c. The critical z-value and the z-score statistic is is d.Which of the following is the correct decision for this hypothesis test:

A graduate student is interested in how viewing different types of scenes affects working memory. For his study, he selects a random sample of 36 adults. The subjects complete a series of working memory tests before and after walking in an urban setting. Before the walk, the mean score on the test of working memory was 9.1. After the walk, the mean score was 1.4 higher. The graduate student has no presupposed assumptions about how viewing different types of scenes affects working memory, so he formulates the null and alternative hypotheses as: H00 : μDD = 0 H11 : μDD ≠ 0 Assume that the data satisfy all of the required assumptions for a repeated-measures t test. The graduate student calculates the following statistics for his hypothesis test: Mean difference (MDD) 1.4 Estimated population standard deviation of the differences (s) 1.6 Estimated standard error of the mean differences (sMDMD) 0.2667 Degrees of freedom (df) 35 The t statistic 5.25 The critical values of t…

The accompanying data were read from a plot (and are a subset of the complete data set) given in an article. The data represent the mean response times for a group of individuals with closed-head injury (CHI) and a matched control group without head injury on 10 different tasks. Each observation was based on a different study, and used different subjects, so it is reasonable to assume that the observations are independent. y = Study 1 2 3 4 5 6 7 8 9 10 Mean Response Time CHI 302 492 658 684 922 1044 1421 1329 1481 1815 t = Control 250 360 475 (a) Fit a linear regression model that would allow you to predict the mean response time for those suffering a closed-head injury from the mean response time on the same task for individuals with no head injury. (Round your answers to four decimal places.) 525 610 740 880 920 1010 1200 (b) Do the sample data support the hypothesis that there is a useful linear relationship between the mean response time for individuals with no head injury and the…

QUESTION 8 Nabisco claims that Chip Ahoy Cookies have an x ̅=28.67 chocolate chips per cookie with a SD=2.67.  You randomly select 15 cookies from a new bag and carefully remove all the chocolate chips from each of the 36 cookies.  You find the mean of the chocolate chips for the 15 cookies is 24.27 chocolate chips per cookie.  Calculate the standard error for the chocolate chips in your experiment.  (round to the nearest hundredth).