You randomly sample 282 sexually active individuals and collect information on their HIV status and History of STDS. At the a=0.05 level, is there evidence of a relationship? STDS Hx HIV Yes No No 80 32 Yes 48 122

Five samples of a ferrous-type substance were used to determine if there is a difference between a laboratory chemical analysis and an X-ray fluorescence analysis of the iron content. Each sample was split into two subsamples and the two types of analysis were applied, with the accompanying results. Assuming that the populations are normal, test at the 0.02 level of significance whether the two methods of analysis give, on the average, the same result. Click here to view the sample analyses. Click here to view page 1 of the table of critical values of the t-distribution. Click here to view page 2 of the table of critical values of the t-distribution. Let sample 1 be the X-ray fluorescence results and let sample 2 be the laboratory chemical results. State the null and alternative hypotheses. Ho: HD H1: HD + Identify the critical region. Select the correct choice below and fill in the answer box(es) to complete your choice. (Round to three decimal places as needed.) O A. t> В. t O C. t<

One thousand men who were working in factory X were screened for HIV on January 1st 2010 and 50 of them were found to be positive for HIV antibodies. The screening was repeated in the same 1000 men on January 1st 2011 and this time 62 men were positive, including the 50 men who were positive on the first screening. Assuming that no one had died or was lost to follow-up, prevalence on January 1st 2010 was: A point prevalence = 6.2%. OB lifetime prevalence = 6.2%. OC. period prevalence = 5%. D. point prevalence = 5%. O E. point prevalence = 1.26%.

The leader of two postpartum women’s support groups is interested in the depression levels of the women in her groups. She administers the Center for Epidemiologic Studies Depression Scale (CES-D) screening test to the members of her groups. The CES-D is a 20-question self-test that measures depressive feelings and behaviors during the previous week. The mean depression level from the screening test for the 10 women in the first group is μ₁ = 16; the mean depression level for the 14 women in the second group is μ₂ = 10. Without calculating the weighted mean for the combined group, you know that the weighted mean is:

PLEASE ANSWER ASAP: A case-control study was conducted to evaluate the relationship between physical activity and coronary heart disease (CHD) in men. A total of 406 men newly diagnosed with CHD were included together with 406 men of similar ages who did not have CHD. The risk of CHD (measured by the OR) was higher among men who were inactive or only moderately active (collectively called ‘inactive’) than among those who were physically active: (See attached image) Odds ratio for inactive men compared to active men= (299 x 136)/(270 x 107)=1.41Suppose there is no misclassification in these data.What would the observed OR have been... 1. If 20% of all the inactive men had been misclassified as active?  2. If 10 % of inactive cases had been misclassified as active?

According to the National Health and Nutrition Examination Survey (NHANES) sponsored by the U.S. government, a random sample of 712 males between 20 and 29 years of age and a random sample of 1,001 males over the age of 75 were chosen and the weight of each of the males were recorded (in kg). Do the data provide evidence that the younger male population weighs more (on average) than the older male population? Use “Y” for ages 20-29 and “S” for ages 75+. It was found that x̅Y=83.4, sY=18.7, x̅S=78.5, and sS=19.0.   a) Is the normality condition met for this test? (see picture) No, since the histograms show skewness and outliers .   Yes, since both sample sizes are larger than 30. No, since both sample sizes, nY and nS, are less than 30. Yes, since it was stated that the two populations are normally distributed.   b)What are the correct degrees of freedom for this test? Group of answer choices 999 1000 1712 1711 711

Among 1815 randomly selected high school students surveyed by the Centers for Diseases Control, 300 said they were current smokers. b. Estimate the variability in such sample proportion by finding SE (p).

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…

A researcher gathered a sample of participants who volunteered for a studying of phobias. She measured anxiety level of participants as they viewed photos of spiders and again when they viewed puppies. Which statistical test is appropriate for this study and why?

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?