What is the null hypothesis

Assignment Help Applied Statistics

Reference no: EM1382241

1. A researcher studying the effects of environment on mood asks participants to sit alone in a waiting room for 15 minutes at the beginning of an experiment. Half of them are assigned to a room with dark blue walls, and the other half are assigned to a room with bright yellow walls. After 15 minutes in the waiting room, each participant is brought into the lab and given a mood-assessment questionnaire. The scores on the mood questionnaire are then examined.

1. Identify the independent variable (s) in the study: _______________________________
2. Identify the dependent variable (s) in the study: _________________________________

2. For the following, state the null (Ho) and the alternative (Hi) hypothesis:

a. Is the mean Hemoglobin level of a group of high-altitude workers different from 16g/cc?

b. Does the mean speed of 50 cars as checked by radar on a I-70 differ from 65mph?

c. Does the mean age of onset of for leukemia for school-age children differ from 11.5 years of age?

3. A graduate student hypothesizes that the mean income for a population is $6,800. The population mean income, in fact, is $6,800. The graduate student rejects the hypothesis. Has an error been made (yes, no), and if so what type of error (type I, type II)?

4. A researcher would like to know whether room temperature will affect eating behavior in rats. (Use the following abstract to achieve your information to the following questions).

a. What is the null hypothesis: ___________________________________________________

b. What is the alternate hypothesis: _______________________________________________

c. What is the research question: _________________________________________________

The lab temperature is usually kept at 72 degrees, and under these conditions, the rats eat an average of 10 grams of food each day. The amount of food varies from one rat to another, forming a normal distribution with a standard deviation of 2. The researcher selects a sample of 4 rats and places them in a room where the temperature is kept oat 65 degrees. The daily food consumption for these rats averaged 13 grams. Do these data indicate that temperature has a significant effect on eating.

5. A researcher is interested in the effects of humidity on the eating behavior of rats. A group of 25 rats is housed in a controlled environment and the researcher measures the amount of food consumed by each rat with the humidity set at 20% and again with the humidity set of 80%. For this study:

a. identify the population: _____________________________________________________________

b. identify the sample: ________________________________________________________________

6. In a psychology class of 90 students, there are 30 males and 60 females. Of the 30 men, only 5 are freshmen. Of the 60 women, 10 are freshman. If you randomly sample an individual from this class:

a. What is the probability of obtaining a female: ____________________________________

b. What is the probability of not obtaining a female: _________________________________

c. What is the probability of obtaining a freshmen: __________________________________

d. What is the probability of obtaining a male freshmen: ______________________________

7. A major corporation in the Northeast noted that last year its employees averaged m = 5.8 absences during the winter season (December to February). In an attempt to reduce absences, the company offered free flu shots to all employees this year. For a sample of n = 100 people who took the shots, the average number of absences this winter was mean = 3.6 with SS = 396.

a. Calculating a simple t-test: Does this data indicate a significant decrease in the number of absences? (Use a one-tailed test with alpha (p) = .05): t critical value ______________________

t test: ________________________ retain/reject: ____________________________

8. Natural Vitamins were advertised as having 750mg of vitamin C per pill. A consumers' group believed the vitamin C was less than (<) advertised. Based on the following sample: Use α level .01.

(* In order to calculate the t score you will need to first calculate the SS, S², S, then perform the t test.)

a. What is the Ho: ________________________________________

b. What is the Hi: ________________________________________

c. What is the t score ? _____________________________________

d. What is the standard estimate of error (Sx¯)? ____________________

e. Was this advertisement justified? _____________________________

f. Were your findings significant? ____________________________

700 780 715 720 760

720 710 740 720 725

760 695 755 730 720

Reference no: EM1382241

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