Researchers studying the link between prenatal vitamin use and autism surveyed the mothers of a random sample of children aged 24 - 60 months with autism and surveyed another separate random sample for children with typical development. Table summarizing the number of mothers in each group who did and did not use prenatal vitamins during the three months before pregnancy (data from Schmidt, 2011) Autism Typical Development Total No vitamin 111 70 181 Vitamin 143 159 302 Total 254 229 483 Complete the hypothesis test for independence between the two variables, use of prenatal vitamins during the three months before pregnancy and autism in Rguroo. What is the value of the test statistic for this test? (Use the Large Sample Z method and please round to two decimal places)

Acne is a common skin disease that affects most adolescents and can continue into adulthood. A study compared the effectiveness of three acne treatments and a placebo, all in gel form, applied twice daily for 12 weeks. The study's 517 teenage volunteers were randomly assigned to one of the four treatments. Success was assessed as clear or almost clear skin at the end of the 12 week period. The results of the study can be seen in the table below. Using the appropriate statistical test, determine if there is significant evidence that the four treatments perform differently. If so, how do they compare.

A researcher is interested in seeing what effect  a particular type of drug has on an intelligence test,  depending on the time of day that the pill is administered. The researcher computes a two-way ANOVA and plots  the resulting cell means on the graph at right. Assuming  that any obvious differences are statistically  significant Is there a main effect for type of pill? Is there a main effect for time of day? Is there an interaction? 4. Describe the findings of the study in everyday terms

Over the past few decades, public health officials have examined the link between weight concerns and teen girls' smoking. Researchers surveyed a group of 273 randomly selected teen girls living in Massachusetts (between 12 and 15 years old). After four years the girls were surveyed again. Sixty-three said they smoked to stay thin. Is there good evidence that more than thirty percent of the teen girls smoke to stay thin? Correctly identify the null and alternative hypotheses:

What source of variation is found in an ANOVA summary table for a within subjects design that is not in an ANOVA summary table for a between subjects design. What happens to this source of variation in a between-subjects design?

Mood variation is related to photoperiod in some people, and the likelihood of depression increases in the winter months. As a result, people often assume that suicide rates increase in winter. A study in Finland (Valtonen et al. 2006) divided the year 1997 into equal halves and compared the number of suicides in “winter” (24 September to 19 March) and “summer” (remainder of year). Out of a total of 1636 suicides, 766 were in winter and 870 were in the summer. Based on these data, estimate the proportion of suicides that occurred in winter, assuming that the suicides were independent. Are the data compatible with a greater suicide rate in winter than summer, based on a 95% confidence interval?

The article “Well-Fed Crickets Bowl Maidens Over” (Nature Science Update, February 11, 1999) reported that female field crickets are attracted to males with high chirp rates and hypothesized that chirp rate is related to nutritional status. The usual chirp rate for male field crickets was reported to vary around a mean of 60 chirps per second. To investigate whether the chirp rate was related to nutritional status, investigators fed 22 male crickets a high protein diet for 8 days, after which chirp rate was measured. Let:  The parameter μμ be the mean chirp rateof male crickets on a high protein diet for 8 days.    Given: The mean chirp rate for the random sample of crickets on the high protein diet was reported to be 65.32 chirps per second with a standard deviation of 12. Research Question: Is there convincing evidence that the mean chirp rate for crickets on a high protein diet implies an advantage in attracting the ladies? It is known that the researchers did not want to…

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…

Use an ANOVA with ? = 0.05 to determine whether there are any significant differences among the three treatment means. If results are significant what is the effect size? Report results in APA format A developmental psychologist is examining the development of language skills from age 2 to 4. Three different groups are obtained, one for each age, with n = 16 children in each group. Each child is given a language-skills assessment test. The resulting data were analyzed with an ANOVA to test for mean differences between age groups. The results of the ANOVA are presented in the following table. Fill in all missing values.             N = , n =  , K = Source SS df MS F Between Txt 20       Within Txt         Total 200