What is the effect of concussions on the brain? Researchers measured the brain sizes (hippocampal volume, in microliters) of 25 collegiate football players with a history of clinician-diagnosed concussion and 25 collegiate football players without a history of concussion. The summary statistics are given in the table. Group Concussion No concussion Group Size 25 25 Mean Standard Deviation 5784 6489 609.3 815.4 Rashmi Singh et al. Relationship of collegiate football experience and concussion with hippocampal volume and cognitive outcomes. JAMA. 2014, 311, 1883-1888.

The table below summarizes baseline characteristics of patients participating in a clinical trial. a) Are there any statistically significant differences in baseline characteristics between treatment groups? Justify your answer. Characteristic Placebo (n = 125) Experimental ( n =125) P Mean (+ Sd. Age 54 + 4.5 53 + 4.9 0.7856 % Female 39% 52% 0.0289 % Less than High School Education 24% 22% 0.0986 % Completing High School 37% 36%   % Completing Some College 39% 42%   Mean (+ Sd. Systolic Blood Pressure 136 + 13.8 134 + 12.4 0.4736 Mean (+ Sd. Total Cholesterol 214 + 24.9 210 + 23.1 0.8954 % Current Smokers 17% 15% 0.5741 % with Diabetes 8% 3% 0.0438

Which is not one of the major assumptions typically associated with parametric tests of significance? A. Random Selection B. Homogeneity of Variance C. Absence of restricted ranges

In a study examining the relationship between socioeconomic status (SES) and academic achievement among high school students, the researchers collected data on 500 students from varying SES backgrounds. The SES was categorized into low, medium, and high. The academic achievement was measured using GPA scores. The following descriptive statistics were obtained: Mean GPA for low SES students: 2.8 Standard deviation of GPA for low SES students: 0.5 Mean GPA for medium SES students: 3.5 Standard deviation of GPA for medium SES students: 0.3 Mean GPA for high SES students: 4.0 Standard deviation of GPA for high SES students: 0.2 a) Calculate the coefficient of variation for each SES group and interpret the results.

A credit score is used by credit agencies​ (such as mortgage companies and​ banks) to assess the creditworthiness of individuals. Values range from 300 to 850 with a credit score over 700 considered to be a quality credit risk. According to a​ survey, the mean credit score is 705.6. A credit analyst wondered whether​ high-income individuals​ (incomes in excess of​ $100,000 per​ year) had higher credit scores. He obtained a random sample of 34 high-income individuals and found the sample mean credit score to be 724.4 with a standard deviation of 84.4. Conduct the appropriate test to determine if​ high-income individuals have higher credit scores at the α=0.05 level of significance. 1) Find: P-value  2) Make a conclusion regarding the hypothesis.

Osteoporosis is a condition in which the bones become brittle due to loss of minerals. To diagnose osteoporosis, an elaborate apparatus measures bone mineral density (BMD). BMD is usually reported in standardized form. The standardization is based on a population of healthy young adults. The World Health Organization (WHO) criterion for osteoporosis is a BMD 2.5 standard deviations below the mean for young adults. BMD measurements in a population of people similar in age and sex roughly follow a Normal distribution. What percent of healthy young adults have osteoporosis by the WHO criterion? Give your answer to two decimal places.

Listed below are the lead concentrations in different Ayurveda medicines. Ayurveda is a traditional medical system commonly used in India. The lead concentrations listed here are from medicines manufactured in the United States. Use a significance level to test the claim that the mean lead concentration for all such medicines is less than 14. 3.0,6.5,6.0,5.5,20.5,7.5,12.0,20.5,11.5,17.5

Nutrition Iron-deficiency anemia is an important nutritional health problem in the United States. A dietary assessment was performed on 56 boys 9 to 11 years of age whose families were below the poverty level. The mean daily iron intake among these boys was found to be 12.40 mg with standard deviation 4.71 mg. Suppose the mean daily iron intake among a large population of 9- to 11-year-old boys from all income strata is 14.41 mg. We want to test whether the mean iron intake among the low-income group is different from that of the general population. You can use the Inferential Statistics page and the Distribution Calculators page in SALT to answer parts of this question. (a) State the hypotheses (in mg) that we can use to consider this question. (Enter != for as needed.) Ho: H₁: (b) Carry out the hypothesis test in part (a) using the critical-value method with an a level of 0.05, and summarize your findings. Find the test statistic. (Round your answer to two decimal places.) Find the…

Is narcissism a more common personality trait today than it was a few decades ago?  It is known that the mean population score on the Narcissistic Personality Inventory (NPI) for students attending University of South Alabama around 20 years ago was μ= 15 (Twenge, 2010).  Interested in the narcissism levels of students in the year 2020, a researcher administers the NPI to a random sample of 25 University of Alabama sophomores this Spring term. The mean NPI score from the researcher’s sample of sophomores is M = 16.5, with s = 3.4. 1. Write the null and alternative hypotheses in symbols. Possible symbols for your answer: H0, H1, μ, M, σ. 2. Calculate the standard error.  3. Find the critical value for the test statistic, assuming alpha = .05 (Use largest [i.e., most conservative] value if exact value not given in the chart)  a) 2.064 b) 1.96 c) 1.98 d) 2.000

Which measure of central tendency would be the most appropriate for this set of data? (3, 8, 1, 6, 3, 4, 11, 3, 4, 3, 5) mode variance mean median