# WEEK 8 – EXERCISES

**WEEK 8 – EXERCISES**

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*Enter your answers in the spaces provided. Save the file using your last name as the beginning of the file name (e.g., ruf_week8_exercises) and submit via “Assignments.” When appropriate, show your work. You can do the work by hand, scan/take a digital picture, and attach that file with your work.*

1. A researcher plans a study in which a crucial step is offering participants a food reward. It is important that the three food rewards be equal in appeal. Thus, a prestudy was designed in which participants were asked which of the rewards they preferred. Of the 60 participants, 16 preferred cupcakes, 26 preferred candy bars, and 18 favored dried apricots. Do these scores suggest that the different foods are differentially preferred by people in general? (Use the .05 significance level.)

a.Use the five steps of hypothesis testing.

b.Sketch the distribution involved.

c.Explain your findings.

2. A high school principal wanted to know if the racial makeup of her teachers mirrored that of the student body. The student body broke down into 47% White, 28% Latino, 15% African American, and 10% other. Of the 65 teachers, 42 were White, 4 were Latino, 15 were African American, and 4 were Other. Do these results suggest that the racial makeup of the faculty members is different from that of the students? (Use the .05 significance level.)

Use the five steps of hypothesis testing and explain your findings.

3. Please make up and discuss research examples corresponding to the various techniques introduced throughout this course. Describe a plausible study for each of the following statistical procedures, indicating how it would apply and what results you would predict. Also include information about the number of participants you would assess and how you would go about estimating effect size and statistical power (when relevant).

a.correlation

b.multiple regression

c.*t* test for independent means

d.*t* test for dependent means

e.ANOVA

f.chi square for goodness of fit

g.chi-square test for independence

**SPSS ASSIGNMENT #8**

**Chi-Square**

**SPSS instructions:**

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**Chi-Square Test for Goodness of Fit:**

Open SPSS

Remember that SPSS assumes that all the scores in a row are from the same participant. In the study presented in #1, there are 20 students, some of whom have been suspended for misbehavior. The primary conflict-resolution style used by each student is also entered. [Ignore the first variable in this analysis.]

When you have entered the data for all 20 students, move to the Variable View window and change the first variable name to “SUSPEND” and the second to “STYLE”. Set the number of decimals for both variables to zero.

Click Analyze à Non-Parametric Tests à Chi-Square

Click the variable “STYLE” and then the arrow next to the box labeled “Test Variable List” to indicate that the chi-square for goodness of fit should be conducted on the conflict-resolution style variable.

Note that “All categories equal” is the default selection in the “Expected Values” box, which means that SPSS will conduct the goodness of fit test using equal expected frequencies for each of the four styles, in other words, SPSS will assume that the proportions of students each style are equal.

Click OK.

**Chi-Square Test for Independence:**

Open SPSS

For #2, you need to add the variable “SUSPEND” to the analysis. Remember that in this problem, we are interested in whether there was an association between conflict-resolution style and having been suspended from school for misbehavior. Since the analysis will involve two nominal variables, the appropriate test is a chi-square test for independence.

Click Analyze à Descriptive Statistics à Crosstabs

Since “SUSPEND” is already selected, click the arrow next to the box labeled “Rows.”

Click the variable “STYLE” and click the arrow next to the box labeled “Columns.”

Click “Statistics” and click the box labeled “Chi-Square.”

Click Continue.

Click “Cells” and click the box labeled “Expected.”

Click Continue.

Click OK.

- The following table includes the primary method of conflict resolution used by 20 students.

Method | Aggressive | Manipulative | Passive | Assertive |

N of Students |
8 | 2 | 2 | 8 |

- Following the five steps of hypothesis testing, conduct the appropriate chi-square test to determine whether the observed frequencies are significantly different from the frequencies expected by change at the .05 level of significance. Clearly identify each of the five steps.
- Explain your response to some who has never had a course in statistics.

- Next, researchers categorized the students based on the primary method of conflict resolution used and whether the student had been suspended from school for misbehavior. These data are presented below.
Method

Suspended | Aggressive | Manipulative | Passive | Assertive | Total |

Yes | 7 | 1 | 1 | 1 | 10 |

No | 1 | 1 | 1 | 7 | 10 |

Total | 8 | 2 | 2 | 8 | 20 |

- Following the five steps of hypothesis testing, conduct the appropriate chi-square test to determine whether the observed frequencies are significantly different from the frequencies expected by change at the .05 level of significance. Clearly identify each of the five steps.
- Calculate the effect size.

- Explain your response to someone who has never had a course in statistics.

- Believing that assertiveness is the most effective method of conflict resolution, the researchers categorized students so that the aggressive, manipulative, and passive categories were combined. These data are presented in the table below.
Conflict Resolution

Suspension from School | Assertive | Other | Total |

Yes | 1 | 9 | 10 |

No | 6 | 4 | 10 |

Total | 7 | 13 | 20 |

- Following the five steps of hypothesis testing, conduct the appropriate chi-square test to determine whether the observed frequencies are significantly different from the frequencies expected by change at the .05 level of significance. Clearly identify each of the five steps.
- Calculate the effect size.

- Explain your results.

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*The deadline for this assignment is 11:59 PM EST on Sunday of Week 8*