# Statistics

Q uestion

## Stats Week 7 a

Description:

p.230, p 4

In two separate studies, the actual difference between the means of a treated group and untreated group is 3 points.  However, in one study, the σ           is very large

M1-M2

and so the 3 points is not found to be significant.   In the other study, the σ

M1-M2

is very small and so the 3 points id found to be significant.  What might have caused this big difference in the σ         for the two studies?

M1-M2

p.231, p8

In the study of the effect of a new drug on the alleviation of asthma symptoms, the

σM for symptom relief in the patient group that received the new drug is 1.45, and the σM for symptom relief in the group that did not receive the new drug 1.22.  Calculate σ

M1-M2

p.241, p2

A large furniture store stations salespeople near its entrance to greet customers and offer assistance in shopping.  The salespeople, who work commission basis, tell the customer their name and hand them a business card.  A psychologist thinks that the salesperson’s intrusiveness might cause customers to buy less furniture rather than more furniture.  She convinces the store’s management to let her study the issue.  Customers are randomly selected to either receive or not receive a salesperson’s offer assistance immediately on entering the store.  The amount of customers’ purchases are then logged as they leave the store.  Here is the data

Amount of Purchase, in U.S. Dollars

Immediate Assistance                                               No Assistance Unless Requested

• 761

2,274                                                                            0

• 2,592
• 0
• 1,037

362                                                                                           0

855                                                                     84

0                                                                                    0

0                                                                                   672

1,273                                                                             0

1. What are the independent and dependent variables in this study?
2. State the null hypothesis and the directional (one-tailed) research hypothesis.
3. Calculate τ and compare it with the tabled critical τ at the .01 and .05 α Can you reject the null hypothesis?

1. 264, 4

State whether the investigator used independent samples, repeated measures, or matched samples:

1. An investigator wants to know if elementary-age children who have experienced the death of a parent are helped by a counseling group consisting of other children who have experienced a death in the family. He randomly selects children for this special counseling group, comparing their emotional adjustment at the beginning of treatment with their emotional adjustment following a year of the specialized group counseling.
2. An investigator wants to know if elementary-age children who have experienced the death of a parent are better helped by a counseling group consisting only of other children who have experienced a death in the family or by a counseling group consisting of children demonstrating a wide range of behavioral and emotional issues. He randomly assigns children to the two groups and compares each group’s emotional adjustment following a year of group counseling.

1. 271, p 7

The following data are from a study of aggression in 40 children (20 pairs) after viewing either violent film or an educational film.  Participants were first matched on gender and their typical aggression level.  Here are participants’ scores on the aggression test given after viewing the film.  Higher scores indicate more aggression.

Pair                                                     Violent Film                           Educational Film

1                                                          26                                            18

2                                                          24                                            12

3                                                          18                                            14

4                                                          27                                            22

5                                                          19                                            13

6                                                          14                                            15

7                                                          24                                            20

8                                                          12                                            9

9                                                          21                                            12

10                                                        15                                            18

11                                                        11                                            7

12                                                        23                                            27

13                                                        23                                            14

14                                                        18                                            8

15                                                        17                                            20

16                                                        12                                            12

17                                                        25                                            17

18                                                        28                                            20

19                                                        13                                            10

20                                                        22                                            14

Calculate t and compare it with the one-tailed critical t at the .01 a level.  Did the children who viewed the violent film show significantly more aggression?

Two-Sample T Test

Think about a study you would like to explore in our future or current career that could be analyze with a two-sample t test.  To help design the study, answering the following:

- Is it an independent group t test matched groups t test or repeated measures t test, and why?

- What is the independent variable?

- What is the dependent variable?

- What do you expect to find if you ran the study? List this out both in statistical language (feel free to make up some number for the results) as well as real-world language.

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• A nswer

### Statistics

Submitted by PROFSTAN on April 26th, 2016 06:53

Price \$30.00

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