A researcher conducts an experiment in a residence for senior citizens to investigate the effect of floor type on the risk of fall-related injury. For 24 randomly selected individuals in the facility, she records the type of flooring (either standard flooring or a new, rubber flooring that absorbs the impact of falls) in their room and whether they sustained at least one fall-related injury in their room over the previous two years. She is interested in whether the rubber flooring is associated with a reduced risk of injury. Her data are available in the file fall.csv.

fall csv :

a. What are the null and alternative hypotheses?

b. What is the value of the test statistic?

c. What is the p-value?

d. State your conclusions in the language of the problem. Use a significance level of 10%.

e. Which assumption is required for the validity of your hypothesis test and why might it be reasonable in this context?

A team of comparative psychologists are interested in the maternal behavior or rats. In an experiment, 10, 20, and 25 day-old rat pups were separated from their mothers. They then recorded the time (in seconds) required for the mother rats to retrieve the pups. The psychologists were interest in whether retrieval time varies with age. The data are given below. What can be concluded with an α of 0.05?

Make an interpretation based on the results.

At least one of the rat pup ages differed on the mother retrieval time.None of the rat pup ages differed on the mother retrieval time.    

e) Conduct Tukey's Post Hoc Test for the following comparisons:
1 vs. 3: difference =  ; significant:  ---Select--- Yes No
1 vs. 2: difference =  ; significant:  ---Select--- Yes No

f) Conduct Scheffe's Post Hoc Test for the following comparisons:
1 vs. 2: test statistic =  ; significant:  ---Select--- Yes No
1 vs. 3: test statistic =  ; significant:  ---Select--- Yes No

An experiment to test the effects of alcohol on motor skills was conducted for a group that drank alcohol and a group that had a placebo. The 22 individuals in the alcohol group had a mean error rate of 4.20 and a standard deviation of 2.20. The 22 individuals in the placebo group had a mean error rate of 1.71 and a standard deviation of 0.72.

a. Construct a 95% confidence interval for the difference in the population means.

b. Interpret the interval.

c. Does the data indicate that drinking alcohol affects motor skills? If “YES”, explain why. If “NO”, what does the data indicate about drinking alcohol and motor skills? No credit for “YES/NO” answer only

Describe in detail, with sketches as appropriate, the requirements for a setup of a mechanical experiment that allows to measure the weight of individual atoms. Provide details of a sensor (eg. scale, mass), the sensor actuation and the sensor read-out (eg. experimental noise, physical principle). How do you prove that the measured atomic mass stems specifically from the atoms you analyse? (Consider environmental sources of measurement noise)

This question featured in an Oscillations section of a past exam paper. Any help greatly appreciated! Thanks.

In an experiment to test the effectiveness of a new sleeping aid, a sample of 12 patients took the new drug, and a sample of 15 patients took a commonly used drug. Of the patients taking the new drug, the average time to fall asleep was 28.6 minutes with a sample standard deviation of 5.2 minutes, and for the patients taking the commonly used drug the average time was 30.7 minutes with a sample standard deviation of 4.1 minutes. Can you conclude that the mean time to sleep is less for the new drug? Assume that population standard deviations are the same. Take ? = 0.01.

a. Use P-value method to test the hypothesis.  

b. Find 99% confidence interval and use it to test the hypothesis.

c. Clearly write your conclusion.

d. If the true mean difference between the sleep times is 2 minutes, what is the probability that we can recognize it.

An experiment is conducted to select a suitable catalyst for the commercial production of a product used in soaps which is called EDA. 10% of catalysts have poor performance, 20% of catalysts have moderate performance, 50% of catalysts have good performance, and 20% of catalysts have excellent performance. Suppose an engineer randomly selects 12 catalysts for testing.

1. Find the probability that 3 of them show poor performance, 4 of them show good performance, and 5 of them show excellent performance,
2.   Find the probability that 3 of them show moderate performance, 1 of them show poor performance, 3 of them show good performance, and 5 of them show excellent performance,

The authors of a paper describe an experiment to evaluate the effect of using a cell phone on reaction time. Subjects were asked to perform a simulated driving task while talking on a cell phone. While performing this task, occasional red and green lights flashed on the computer screen. If a green light flashed, subjects were to continue driving, but if a red light flashed, subjects were to brake as quickly as possible. The reaction time (in msec) was recorded. The following summary statistics are based on a graph that appeared in the paper.

n = 47      x = 53   s = 65

a) Construct a 95% confidence interval for μ, the mean time to react to a red light while talking on a cell phone. (Round your answers to three decimal places.)

(_________ , _________)

b) Suppose that the researchers wanted to estimate the mean reaction time to within 7 msec with 95% confidence. Using the sample standard deviation from the study described as a preliminary estimate of the standard deviation of reaction times, compute the required sample size. (Round your answer up to the nearest whole number.)

n = ?

A team of comparative psychologists are interested in the maternal behavior or rats. In an experiment, 10, 20, and 25 day-old rat pups were separated from their mothers. They then recorded the time (in seconds) required for the mother rats to retrieve the pups. The psychologists were interest in whether retrieval time varies with age. The data are given below. What can be concluded with an α of 0.05?

Make an interpretation based on the results.

At least one of the rat pup ages differed on the mother retrieval time.None of the rat pup ages differed on the mother retrieval time.    

e) Conduct Tukey's Post Hoc Test for the following comparisons:
1 vs. 3: difference =  ; significant:  ---Select--- Yes No
1 vs. 2: difference =  ; significant:  ---Select--- Yes No

f) Conduct Scheffe's Post Hoc Test for the following comparisons:
1 vs. 2: test statistic =  ; significant:  ---Select--- Yes No
1 vs. 3: test statistic =  ; significant:  ---Select--- Yes No

Design an experiment that tests the effect of body temperature on the aerobic capacity in an animal of your choice. What variables would you measure, and how? Include detail about experimental design and instrumentation, to show your understanding of how data are acquired. Present hypothetical data (in graphical form), which support your predictions. Make sure to label your graphs accurately and precisely, and use reasonable values (and units) for parameters measured.