Suppose you want to test the mean of quiz scores Ho : H 2 72 versus H, : H < 72. Which of the following possible results based on a sample of size 25 from a normal population gives the strongest evidence to reject Ho in favor of H,? O a. X= 68, S = 6 O b. X= 67, S = 8 O c. X= 69, S = 5 O d. X= 70, S= 4

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15. Research results suggest that IQ scores for boys Plomin, 2006). A typical study looking at 10-year-old are more variable than IQ scores for girls (Arden & size would be reported in a journal article. children classifies participants by gender and by low. average, or high IQ. Following are representing the research results. Do the data indicate a significant difference between the frequency distri- butions for males and females? Test at the .05 level of significance and describe the difference. hypothetical data 1 IQ Low Average High Вoys 18 42 20 80 Girls 12 54 14 80 n = 160 Int Ava

Imagine a researcher asks a sample of five people to drive two types of cars and rate each of them on a scale of 1 to 25. The researcher wants to know: Is there is a difference in the ratings of the two types of cars. Below are the data collected: Type A: 20, 10, 11, 23, 7 Type B: 10, 11, 4, 12, 1 what type of T Test would be appropriate

Two computer users were discussing tablet computers. A higher proportion of people ages 16 to 29 use tablets than the proportion of people age 30 and older. The table below details the number of tablet owners for each age group. Test at the 1% level of significance. (For subscripts let 1 = 16-29 year old users, and 2 = 30 years old and older users.)   16–29 year olds 30 years old and older Own a Tablet 69 231 Sample Size 625 2,313 NOTE: If you are using a Student's t-distribution for the problem, including for paired data, you may assume that the underlying population is normally distributed. (In general, you must first prove that assumption, though.) Part (a) State the null hypothesis. H0: p1 < p2 H0: p1 > p2      H0: p1 ≠ p2 H0: p1 = p2 H0: p1 ≥ p2 Part (b) State the alternative hypothesis. Ha: p1 < p2 Ha: p1 ≠ p2      Ha: p1 = p2 Ha: p1 > p2 Ha: p1 ≤ p2 Part (c) In words, state what your random variable  P'1 − P'2  represents. P'1 −…

Children with autism differ significantly from children without autism on tests of varbal ability.   repeated measures? or ind. with two tails?

If you look at the differences between the means, once with 10 participants and one mean with 20 participants. (same data set) One mean difference is very large, but non-significant and the other is very small, but came out significant. What could be the reason for this outcome? (My difference in means was with 10 participants: -1.1 and with 20 participants: -5.1)

For the given scenario, determine the type of error that was made if any.(begin by determining the null and alternative hypothesis). A new whitening toothpaste advertises for shades as the mean number of shades the toothpaste whitens your teeth. One user claims that the mean number of shades the toothpaste whitens your teeth is different from four shades. The user conducts a hypothesis test and fails to reject the null hypothesis. Assume that in reality, the mean number of shades the two piece white is your teeth is for shade. Was an error made? If so, what type? A, B, C? A.Yes; type 2 error B.Yes; type 1 error C.No; correct decision

The wrong alternative. One of your friends is testing the effect of drinking coffee on the duration of cold symptoms. The common cold lasts, on average, 6 days. Your friend starts with no expectations as to whether drinking coffee will have any effect on cold duration. After seeing the results of the experiment, in which the average cold duration was less than 6 days, your friend tests a one-sided alternative about the population mean cold duration when drinking coffee, H0: lcoffee = 6 На: Which gives a one-sided P value P = 0.0465. Explain why your friend should have used a two-sided hypothesis. Hcoffee < 6

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