esearchers have noted a decline in cognitive functioning as people age (Bartus, 1990). However, the results from other research suggest that the antioxidants in foods such as blueberries may reduce and even reverse these age-related declines (Joseph et al., 1999). To examine this phenomenon, suppose that a researcher obtains a sample of n = 16 adults who are between the ages of 65 and 75. The researcher uses a standardized test to measure cognitive performance for each individual. The participants then begin a 2-month program in which they receive daily doses of a blueberry supplement. At the end of the 2-month period, the researcher again measures cognitive performance for each participant. The results show an average increase in performance of MD = 7.4 with SS = 1215. Does this result support the conclusion that the antioxidant supplement has a significant effect on cognitive performance? Use a two-tailed test with α = .05. Show your computations.

Imagine you are a statistical consultant and your client, a weightlifting supplement company, is looking to see if their product is effective in increasing muscle mass gained over a training cycle. You randomly sampled 20 female weightlifters and assigned them to take the supplement and 20 to take a placebo. You have both groups run the same controlled training program over 12 weeks and calculated their whole body lean mass difference in pounds from the beginning to the end of the program. Can you infer that the supplement group gained more muscle mass on average than the placebo group? Use a = 0.05 for any hypothesis test. પ્રમ 1) State the research question in one sentence and use the question to determine the parameter we are using to conduct statistical inference. Describe this parameter in one sentence using symbols and a description. manu Aren

As men age, their testosterone levels gradually decrease. This may cause a reduction in energy, an increase in fat, and other undesirable changes. Do testosterone supplements reverse some of these effects? A study in the Netherlands assigned 237 men aged 60 to 80 with low or low-normal testosterone levels to either a testosterone supplement or a placebo. Why is it necessary to include a control group in this experiment? Every experiment needs a control group in order to make proper comparisons between treatments. A control group is necessary to balance the effects of other variables among the treatment groups. A control group is necessary so any differences in the effects of the treatments can be distinguished from chance differences between the groups. A control group helps avoid confounding and reduces variability in the response variable. A control group is used to provide a baseline for comparing the effects of other treatments.

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Oishi and schimmack (2010) reportthe people who move from the home to home frequently as children tend to have lower than average levels of well-being as adults. to further examine this relationship a psychologist obtains a sample of n =12 young people adults who each experience five or more different homes before they were 16 years old. these participants were given a standard well-being questionnaire for which the general population has an average score of u =40. The well-being scores for this sample are as follows: 38, 37, 41, 35, 42, 40, 33, 33, 36, 38, 32, 39 a) on the basis of this sample is well-being for frequent movers significantly different from well-being is a general population?  use a two tailed test with a = .05. b) compute the estimated Cohen's d to measure the size of the difference.  c) write a sentence showing how the outcome of the hypothesis test and the measure of effect size would appear in a research report.

In 1990, 58% of Americans 18 years old and older reported they have a great deal of concern regarding air pollution. A recent poll found that 592 of 1004 Americans 18 years old or older stated that they have a great deal of concern regarding the level of air pollution in American. Is there evidence to conclude that the current proportion of Americans having a great deal of concern about the level of air pollution in America is different from the 1990 proportion, with a 10% level of significance?  State the null hypothesis, alternative hypothesis, test statistic, p-value and conclusion.

Does posting calorie content for menu items affect people’s choices in fast food restaurants? According to results obtained by Elbel, Gyamfi, and Kersh (2011), the answer is no. The researchers monitored the calorie content of food purchases for children and adolescents in four large fast food chains before and after mandatory labeling began in New York City. Although most of the adolescents reported noticing the calorie labels, apparently the labels had no effect on their choices. Data similar to the results obtained show an average of M = 786 calories per meal with s = 85 for n = 100 children and adolescents before the labeling, compared to an average of M = 772 calories with s = 91 for a similar sample of n = 100 after the mandatory posting. Use a two-tailed test with α = .05 to determine whether the mean number of calories after the posting is significantly different than before calorie content was posted. Calculate r2 to measure effect size for the mean difference.

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…

A particular paper described a study of children who were underweight or normal weight at age 2. Children in the sample were classified according to the number of sweet drinks consumed per day and whether or not the child was overweight one year after the study began. Is there evidence of an association between whether or not children are overweight after one year and the number of sweet drinks consumed? Assume that it is reasonable to regard the sample of children in this study as representative of 2 to 3 years old children and then test the appropriate hypotheses using a .05 significance level. (Round your answer to two decimal places.) Number of Sweet Overweight? Drinks Consumed per Day Yes No 22 930 1 73 2071 2 56 1681 3 or More 102 3389 x2 = | P-value interval Op< 0.001 O 0.001 s p < 0.01 O 0.01 sp < 0.05 O 0.05 sp < 0.10 Op2 0.10 There is --Select--- v to conclude that there is an association between whether or not children are overweight after one year and the number of sweet…

Researchers investigate how the presence of cell phones influence the quality of human interaction.  Subjects are randomly selected from a population and divided into an experimental group that is asked to leave their phones in the front of the room and a control group that are not asked to leave their cell phones at the front of the room.  Subjects are left alone for 10 minutes and then asked to take a survey designed to measure quality of interactions they had with others in the experiment.  What statistical test is appropriate?