A study was conducted that investigated the gene ACTN3, which encodes a protein that functions in fast-twitch muscle fibres. People can be classified according to which genotype of this gene they have, RR, RX or XX. The study included a sample of elite sprinters and a sample of endurance athletes. The researchers are investigating whether there is an association between the genotype classification and the type of athlete (sprinters or endurance). What is the null and alternative hypotheses for the test?

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A team of researchers is interested in the effect on physical health of writing about thoughts and feelings associated with traumatic life events (expressive writing). The researchers recruit 30 undergraduate students to take part in the study and randomly assign them to be in an expressive writing group or a control group. Students in the expressive writing group are instructed to write four 20 - minute essays over four consecutive days about their most traumatic life experiences. Students in the control group write four 20 – minute essays over consecutive days describing their plans for that day. One week later, the researchers ask the students to rate their overall level of physical health (on a scale 0 = very poor health, to 100 = perfect health). EWG: 75, 86, 77, 91, 68, 74, 62, 93, 82, 79, 94, 56, 79, 86, 90, 97 CWG: 81, 76, 71, 70, 62, 50, 58, 63, 76, 64, 65, 72, 52, 59 The researchers were interested in identifying a positive or a negative health effect of expressive writing.…

An article included data from a survey of 2500 hiring managers and human resource professionals. The article noted that many employers are using social networks to screen job applicants and that this practice is becoming more common. Of the 2500 people who participated in the survey, 1250 indicated that they use social networking sites (such as Facebook, MySpace, and LinkedIn) to research job applicants. For the purposes of this exercise, assume that the sample is representative of hiring managers and human resource professionals -Why can this sampling distribution be considered normal? Explain and show why. -Construct a 95% confidence interval for the true population proportion of employers who use social networking sites to screen job applicants. Be sure to write a conclusion sentence that interprets your interval. (You may use Excel for this -Construct a 99% confidence interval for the true population proportion of employers who use social networking sites to screen job applicants.…

A study was conducted that investigated the gene ACTN3, which encodes a protein that functions in fast-twitch muscle fibres. People can be classified according to which genotype of this gene they have, RR, RX or XX. The study included a sample of elite sprinters and a sample of endurance athletes. The researchers are investigating whether there is an association between the genotype classification and the type of athlete (sprinters or endurance). What type of hypothesis test would be appropriate for this study? Explain your answer in one or two sentences.

A study indicates that CB radio use speeds up activity in the brain. As part of a randomized crossover study, 36 participants were fitted with a CB radio device on each ear and then underwent two positron emission topography, or PET, scans to measure brain glucose metabolism. During one scan, the CB radios were both turned off. During the other scan, an automated 40- minute muted signal was sent to the radio on the right ear. The order of when the signal was received (for the first or second scan) was randomized. Comparison of the PET scans showed a minor increase in activity in the part of the brain closest to the antenna during the transmission of the automated signal. Was this an observational study or an experiment? Explain why. O The study is an observational study because the reseashers cannot control the response variable during the signal. O The study is an observational study because the researchers only observe values of the response and explanatory variables. O The study is…

A journal reported a study examining the possible impact of air pollution on the weight of babies. Researchers found that 9% of 174 babies bom to mothers who were exposed to heavy doses of air pollution in a city were classified as having low birthweight. Only 5% of 2300 babies bom in another hospital in the city whose mothers had not been exposed to air pollution were similarly classified. Does this indicate a possibility that air pollution might be linked to a significantly higher proportion of low-weight babies? a) Test an appropriate hypothesis at a = 0.10 and state your condlusion. b) If you concluded there is a difference, estimate that difference with a confidence interval and interpret that interval in context. Identify the test statistic. (Round to two decimal places as needed.) Identify the P-value from the output of the hypothesis test. (Round to three decimal places as needed.) State the conclusion. Ho. There V sufficient evidence at the a = 0.10 level of significance to…

The Stanford University Heart Transplant Study was conducted to determine whether an experimental heart transplant program increased lifespan. Each patient entering the program was officially designated a heart transplant candidate, meaning that he was gravely ill and might benefit from a new heart. Patients were randomly assigned into a treatment and control groups. Patients in the treatment group received a transplant and those in the control group did not. The table below displays how many patients survived and died in each group.     control treatment alive 4 24 dead 30 45 Explain why we cannot construct a confidence interval or a hypothesis test (hint: consider the conditions).

A study was conducted about the safety and privacy of teens online presence.  A random sample of 593 teenagers were asked if they felt that they were easy to find online from their Facebook profiles.  Sixty-two girls of 325 teen girls with profiles say that they are easy to find, while 75 boys of 268 teen boys with profiles say the same.  Is there evidence of a real difference between boys and girls?

A study was conducted that investigated the gene ACTN3, which encodes a protein that functions in fast-twitch muscle fibres. People can be classified according to which genotype of this gene they have, RR, RX or XX. The study included a sample of elite sprinters and a sample of endurance athletes. The researchers are investigating whether there is an association between the genotype classification and the type of athlete (sprinters or endurance). Observed counts XX RX RR Total Endurance 55 49 30 134 Sprinters 49 95 50 194 Total  104 144  80  328 The observed test statistic was 9.38 (2dp) and the associated p-value was 0.009192 (6dp). Make a decision and conclusion for this hypothesis test in context. Use a significance level of 1% (α = 0.01).