For all the experiments and calculations assume normality and =0.05.

You need to respond to 4 out of the 5 experiments (25 points each). The response needs to have the following information:

• Experiment title.
• Hypotheses: both alternative and the null (5 points).
• Mean and standard deviation of each group (5 points).
• Clear indication of the hypothesis test being conducted and the obtained statistic (10 points).
• The results and conclusion (5 points).

Scenarios Experiment 1: Does early exposure to school affect IQ?

An educator wants to determine whether early exposure to school will affect IQ. He enlists the aid of the parents of 24 of preschool-age children to participate in this experiment, 12 children go to preschool and 12 children stay home. At the end of 2 years, the IQs of all the children are measured. The results are as follows:

IQ of children who went to preschool	IQ of children who stayed home
110	114
121	118
107	103
117	112
115	117
112	106
130	125
116	113
111	109
120	122
117	116
106	104

Experiment 2: Does reducing muscle tension reduce headaches?

Muscle tension in the head region has been associated with tension headaches. Therefore, a physician reasoned that if the muscle tension could be reduced, perhaps the headaches would decrease or go away altogether. They design an experiment in which nine participants with tension headaches participate. The participants keep daily logs of the number of headaches they experience during a 2-week baseline period. Then they are trained to lower their muscle tension in the head region, using a biofeedback device. For this experiment, the biofeedback device is connected to the frontalis muscle, a muscle in the forehead region. The device tells the participant the amount of tension in the muscle to which it is attached (in this case, frontalis) and helps them achieve low tension levels. After 6 weeks of training, during which the participants have become successful at maintaining low frontalis muscle tension, they again keep a 2-week log of the number of headaches experienced. The following are the number of headaches recorded during each 2-week period.

Participant #	# headaches before training	# headaches after training
1	17	2
2	13	7
3	6	2
4	5	3
5	5	6
6	10	2
7	8	1
8	6	0
9	7	2

Experiment 3: Does sleep deprivation affect sustained attention?

A sleep researcher conducts an experiment to determine whether sleep loss affects the ability to maintain sustained attention. Fifteen individuals are randomly divided into the following three groups of five participants each: group 1, which gets the normal amount of sleep (7-8 hours); group 2, which is sleep-deprived for 24 hours; and group 3, which is sleep-deprived for 48 hours. All three groups are tested on the same auditory vigilance task. Participants are presented with half-second tones spaced at irregular intervals over a 1-hour duration. Occasionally, one of the tones is slightly shorter than the rest. The participant's task is to detect the shorter tones. The following percentages of correct detections of the short tone were observed:

Not sleep deprived	Sleep deprived 24 hours	Sleep deprived 48 hours
85	60	60
83	58	48
76	76	38
64	52	47
75	63	50

Experiment 4: Does memory change with age?

A researcher conducts an experiment to test whether memory changes with age. They recruited 24 participants separated into four age groups. The groups differ according to the age of subjects. In group 1, all participants are 30 years old; group 2, 40 years old; group 3, 50 years old; and group 4, 60 years old. Assume that the participants are all in good health and that the groups are matched on other important variables such as years of education, IQ, gender, motivation, and so on. Each participant is shown a series of nonsense syllables (a meaningless combination of three letters such as DAF or FUM) at a rate of one syllable every 4 seconds. The series is shown twice, after which participants are asked to write down as many of the syllables as they can remember. Below is number of syllables remembered by each participant:

30 years old	40 years old	50 years old	60 years old
14	12	17	13
13	15	14	10
15	16	14	7
17	11	9	8
12	12	13	6
10	18	15	9

Experiment 5: What is the relationship between soft drinks and obesity?

The director of an obesity clinic in a large northwestern city believes that drinking soft drinks contributes to obesity in children. To determine whether a relationship exists between these two variables, she conducts the following pilot study. Eight 12-year-old male volunteers are randomly selected from children attending a local junior high school. Parents of the children are asked to monitor the number of soft drinks consumed by their child over a 1-week period. The children are weighed at the end of the week and their weights converted into body mass index (BMI) values. The BMI is a common index used to measure obesity and takes into account both height and weight. An individual is considered obese if they have a BMI value 30. The following data are collected:

Child	# of soft drinks consumed	BMI
1	3	20
2	1	18
3	14	32
4	7	24
5	21	35
6	5	19
7	25	38
8	9	30