# statistical significance

This will be a two part assessment
PART ONE:
When we examine the relationships between variables where two or more variables are characterized by nominal or categorical groups, we may use a chi-square test of significance. The chi-square test examines the statistical significance of the differences between observed and expected frequency count in each cell of the table. The chi-square test tells you only whether a statistical significance of difference exists between groups on some other categorical variable (neither strength nor direction).
Resources
Required Resources
The following resource is required to complete the assessment.
Resources
Click the links provided to view the following resources:
assessment5a.sav.
assessment5b.sav.
assessment5c.sav.
assessment5d.sav.
SPSS Software
You are required to have the following software to complete your assessments throughout the course:
Note: Versioning: This software is routinely updated. While version 22 of the IBM SPSS Statistics is recommended, older versions may be used if you already own or have access to them for the duration of this course. Arrange the required statistical software for your operating system (PC or Macintosh).
If you have access to statistical software such as SAS or Excel with the appropriate add-in such as XLSTAT, you may use these as long as they meet the requirements of this course.
? Assessment Instructions
Answer the questions below, following the Submission Requirements as specified at the end of the assessment.
Assessment Concepts
Question Concept
Question 1 SPSS: One-Variable Chi Square
Question 2 SPSS: One-Variable Chi Square
Question 3 Chi-Square as a Test of Independence
Question 4 SPSS: Two-Variable Chi-Square
Question 5 Measures of Effect Size
Question 6 Power and the Factors Affecting It
Question 7 Power and the Factors Affecting It
Question 8 Correlational Studies
Question 9 Correlation: Relationship Direction
Question 10 SPSS: Scatterplot
Question 11 SPSS: Pearson?r
Question 12 SPSS: Pearson?r
Question 1
Complete the following steps:
0. Open the SPSS file?assessment5a.sav?linked in the Resources under the Required Resources heading.
1. At the top of the screen, click on?Data, then select?Weight Cases.
2. Click on?Weight Cases By,?click on?Count, then click on the?arrow?next to?Frequency Variable?to send it over to the Test Variable box.
3. On the toolbar, click?Analyze, then?Nonparametric Tests, then?Legacy Dialogs, the?Chi Square.
4. Click on?Favorite Color, then click on the?arrow?to send to the?Test Variable List?window.
5. Under?Expected Values, select?Value, then enter the following four values in order:?43, 58, 253, 414.
6. Click?OK?and copy and paste the output to your Word document.
Question 2
There are 218 first graders in an elementary school. Of these first graders, 86 are boys, and 132 are girls. School-wide, there are 753 boys and 1063 girls. The principal would like to know if the gender ratio in first grade reflects the gender ratio across the school.
Complete the following:
0. Identify the null hypothesis.
1. What are the degrees of freedom (df)?
2. Complete the table (complete in SPSS and paste the output into your Word document):
Question 2
Men Women
Number Observed Number Expected Number Observed Number Expected
? ? ? ?
0. Calculate ?? in SPSS and paste the output into your Word document.
1. Can you reject the null hypothesis at a = .05?
Question 3
You recently read a magazine article stating that professionals who attended college online tend to earn higher salaries than professionals who attended brick-and-mortar universities. Identify this study’s two variables.
Question 4
Complete the following steps:
0. Open the SPSS file?assessment5b.sav?linked in the Resources under the Required Resources heading.
1. At the top of the screen, click on?Data, then select?Weight Cases.
2. Click on?Weight Cases By, click on?Count, then click on the arrow next to?Frequency Variable?to send it over to the Test Variable box.
3. On the toolbar, click?Analyze, then?Descriptive Statistics, then?Crosstabs.
4. Click on?Team Placement, then click on the?arrow?to send to the?Rows?window.
5. Click on?Gender, then click on the?arrow?to send to the?Columns?window.
6. Click on the?Statistics?button, then check the box for Chi-Square. Click?Continue.
7. Click on the?Cells?button, then check the box for?Expected. Click?Continue.
8. Click?OK, and copy and paste the output to your Word document.
9. Highlight the chi-square and significance values in the output. Write the chi-square results as you might see them in a journal.
Question 5
Group A (n = 12) has a mean score of 7.42. Group B (n = 12) has a mean score of 6.00. Standard deviation for scores across all participants is 1.369. Group A’s mean is significantly higher than Group B’s mean (?t?= 2.84, a < .01).
0. Calculate effect size using Cohen’s d and effect size?r.
1. Based on the effect size, it there a practical difference between Groups A and B?
Question 6
Assume Cohen’s?d?to be approximately .40. If conducting an independent samples?t?test (two-tail, a= .05), how many participants will you need in each group to achieve 90 percent (.90) power?
Question 7
Assume effect size ? to be approximately .29. If conducting a one-way ANOVA (three groups, a = .05), how many participants will you need in each group to achieve 80 percent (.80) power.
Question 8
Which of the following scenarios might be analyzed using a correlation?
? The effectiveness of training A versus training B in raising skill level.
? Minutes spent exercising per week and physical fitness level.
? Income level and the number of visits to a financial planner.
? Beer brand preference among college students.
Question 9
Indicate if you expect the relationship between the following variables to be negative (-), positive (+), or zero (0):
? Size of yard and size of landscaping bill.
? Years of education and income level.
? Hours of TV watched per week and physical fitness level.
? Number of siblings and number of pets.
? Hours spent studying and exam scores.
Question 10
Complete the following steps:
0. Open the SPSS file?assessment5c.sav?linked in the Resources under the Required Resources heading.
1. At the top of the screen, click on?Graphs, then select?Legacy Dialogs, then?Scatter/Dot.
2. Click on?Simple Scatter,?and select?Define.
3. Click on?Exam 1 (X), then click on the?arrow?next to?X Axis?to send it over to the X Axis box.
4. Click on?Exam 2 (Y), then click on the?arrow?next to?Y Axis?to send it over to the Y Axis box.
5. Click?OK, then copy and paste the scatterplot output to your Word document.
Question 11
Complete the following:
0. Open the SPSS file?assessment5c.sav.
1. At the top of the screen, click on?Analyze, then select?Correlation, then?Bivariate.
2. Click on?Exam 1 (X), then click on the?arrow?to send it over to the Variables box.
3. Click on?Exam 2 (Y), then click on the?arrow?to send it over to the Variables box.
4. Click?OK,?then copy and paste the correlation output to your Word document.
Question 12
Complete the following steps after opening the SPSS file?assessment5d.sav?linked in the Resources under the Required Resources heading:
0. Create a scatterplot. Copy and paste the scatterplot output to your Word document.
1. Based on the scatterplot, what is the expected strength and direction of the correlation?
2. Identify the null hypothesis.
3. Calculate Pearson r. Copy and paste the correlation output to your Word document.
4. Based on the correlation output (two-tailed test), can the null hypothesis be rejected? If the null can be rejected, how confident can you be that the results are not due to chance?
5. Report the results as you might see them in a journal.
Submission Requirements
? Submit all answers in one Word document (do not submit multiple files).
? Show your work for questions that require calculations.
? Ensure your answer to each problem is clearly visible (you may want to highlight your answer, or use a different font color, to set it apart).
PART TWO
Assessment Instructions
As a mental health professional, you are expected to remain current on field research and apply this new knowledge in your work.
Complete the following:
? Select an area of interest within psychology.
? Use the library to locate one peer-reviewed journal article that uses the interpretation of statistical analysis to resolve an issue in the field. Select an article that uses quantitative (not qualitative) analyses.
? Write a 2 page critically analyzing the article. Consider the interpretation and selection of the supporting statistical analyses. To do this, complete the following:
? Explain the analysis and describe the decision that was made. Was the null hypothesis rejected, or did the article fail to reject the null hypothesis? Provide examples of the statistical language used and translate the examples from statistical language to real-world language.
? Evaluate the research and discuss areas of strength and areas of weakness in the study design, research process, and interpretation and description of the results.
? Explain whether you think the conclusions accurately reflect the analysis. Use both statistical and real-world language to support your opinion.
Be sure to communicate in a manner that respects the dignity, cultural and ethnic backgrounds, and individual uniqueness of others.