10:19 AM Tue Dec 12Quick NotesועדAa[0]53%in a research Study analyzingthe effect of Caffeine onCognitive ability, research Planto decrease their Sample Size.Assuming all Other Conditionsremain the same would thisOrChange results in alargersmaller error bound for theirStudy's results?3

The research study analyzes the effect of caffeine on cognitive ability.It is planned by the…

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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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Attractiveness of body types has been a large discussion relating to effects on youth and culture. Unhealthy levels of BMI are often associated with beauty. A researcher decided to study how young heterosexual adults body type preferences related to BMI. Participants were asked to use a computer program to design their desired partner. The program then calculated the BMI of the designed partners. The table summarizes the results based on a SRS of 35 men and 48 women. BMI designed by men n=35 x-bar=18.850 stdev=1.750 SE Mean 0.277 BMI designed by women n=48 x-bar=25.860 stdev=4.215 SE Mean 0.625 Use this information to conduct a test to decide if male and/or female body type preferences are associated with healthy BMI measurements. You should have two complete tests here. You may assume the populations are normally distributed.
Studies indicate that excessive noise at night can affect weight gain. One study of n = 127 rats compared the weight gain of rats exposed to excessive noise at night and the weight gain of rats in a quiet night environment. Sample statistics for the study are given in the table below. Use this information to determine if there is significant evidence that weight gain of rats exposed to excessive noise at night is different on average than weight gain of rats in a quiet night environment. Excessive noise at night environment (Group 1) Quiet night environment (Group 2) Sample mean (grams) 22.4 19.9 Sample standard deviation (grams) 6.4 3.8 Observations/Sample size 69 58 Is this a one-tailed or a two-tailed test? Explain in one or two sentences.
Identifying individuals with a high risk of Alzheimer’s disease usually involves a long series of cognitive tests. However, researchers have developed a 7-Minute Screen, which is a quick and easy way to accomplish the same goal. The question is whether the 7-Minute Screen is as effective as the complete series of tests. To address this question, Ijuin et al. (2008) administered both tests to a group of patients and compared the results. The following data represent results similar to those obtained in the study. Scores in 7minute-screen (Y) Scores in Cognitive series (X) 0 11 4 19 6 22 8 20 5 14 4 13 A) Calculate the Pearson correlation for these data. B) If the researchers centered the variable of 7-minute screen (i.e., every score in this variable minus its Mean), what would be the new value of correlation? C) Is the correlation statistically significant? Use a two-tailed test with α = .05.
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?
Using the latest in medical technology, an orthopedic doctor has developed a new surgical procedure that he believes is an improvement over the standard procedure. He wants to study whether the mean recovery time of patients who have the new procedure is less than the mean recovery time of patients who have the standard procedure. The doctor studies a random sample of 11 patients who have the new procedure and a random sample of 9 patients who have the standard procedure. (These samples are chosen independently.) The doctor records each patient's recovery time (in days). The patients who had the new procedure have a sample mean recovery time of 367.3 with a sample variance of 2851.8. The patients who had the standard procedure have a sample mean recovery time of 420.9 with a sample variance of 98.1. Assume that the two populations of recovery times are approximately normally distributed. Can the doctor conclude, at the 0.01 level of significance, that the population mean of the…
Computer-mediated communication (CMC) is a form of interaction that heavily involves technology (e.g., instant messaging, email). A study was conducted to compare relational intimacy in people interacting via CMC to people meeting face-to-face (FTF). Participants were 48 undergraduate students, of which half were randomly assigned to the CMC group and half assigned to the FTF group. The variable of interest, relational intimacy score, was measured (on a 7-point scale) for each participant after each of three different meeting sessions. Summary statistics for the first meeting session are given here. The researchers hypothesized that, after the first meeting, the mean relational intimacy score for participants in the CMC group would be lower than the mean relational intimacy score for participants in the FTF group. Test the researchers’ hypothesis using α = .10. CMC FTF Number…
Identifying individuals with a high risk of Alzheimer’s disease usually involves a long series of cognitive tests. However, researchers have developed a 7-Minute Screen, which is a quick and easy way to accomplish the same goal. The question is whether the 7-Minute Screen is as effective as the complete series of tests. To address this question, Ijuin et al. (2008) administered both tests to a group of patients and compared the results. The following data represent results similar to those obtained in the study. Patient 7-Minute Screen Cognitive Series A 3 7 B 7 15 C 4 14 D 5 13 E 7 9 F 5 15 G 11 25 The alternative hypothesis in words and null hypothesis in symbols for a two-tailed test is
Researchers 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.
A team of epidemiologists at the Mayo Clinic wanted to find whether there is an association between obesity and cardiovascular disease (CVD). They conducted a prospective cohort study following obese and non-obese individuals who were free of CVD at the beginning of study for five years. The investigators were also interested in assessing age as a potential confounder, effect modifier, or both. Use the data below to answer the accompanying questions. CVD No CVD Total Obese 10 90 100 Not Obese 35 465 500 Total 45 555 600 CVD No CVD Total Obese 36 164 200 Not Obese 25 175 200 Total 61 339 400 1. Compute the appropriate measure of association for those who were less than age 50. 2. Compute the appropriate measure of association for those who were older or equal to age 50. 3. Compute the crude measure of association? 4. List three attributes that age must satisfy before it could…
Identifying individuals with a high risk of Alzheimer’s disease usually involves a long series of cognitive tests. However, researchers have developed a 7-Minute Screen, which is a quick and easy way to accomplish the same goal. The question is whether the 7-Minute Screen is as effective as the complete series of tests. To address this question, Ijuin et al. (2008) administered both tests to a group of patients and compared the results. The following data represent results similar to those obtained in the study: Patient 7-Minute Screen Cognitive Tests A 3 11 B 8 19 C 10 22 D 8 20 E 4 14 F 7 13 G 4…

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in a research Study analyzing the effect of Caffeine on Cognitive ability, research Plan to decrease their Sample Size. Assuming all other Conditions remain the same would this results in a Or Change larger Smaller error bound for their Study's results?