EDUR 8131
Educational Statistics 1

Notes 5c: Correlated Samples t-test
Notes 6: Correlation Coefficient, Pearson's r

(1) Summary Presentation

• Document: Correlated Samples t-test and Pearson Correlation Word
• Document: Correlated Samples t-test and Pearson Correlation PDF
• Video: Correlated Samples t and Pearson r (51 minutes)
• New: Brief video showing enter data in SPSS in preparation to run Pearson correlation https://www.youtube.com/watch?v=jexXeAoymh4 (my notes with SPSS do not show how data were enter because an existing data file was used). For JASP, the process is the same except one enters data into a spreadsheet in the same way as illustrated in this video, then open spreadsheet in JASP to run the correlation.

(2) Reporting statistical results in APA style (Word Documents so you can copy and paste tables)

• Paired-samples (correlated-samples) t-test 
• Pearson Correlation Coefficients   

(3)  JASP Software 

• Correlated Samples t-test (Summary Presentation Notes 5c)
• Pearson Correlation r (Summary Presentation Notes 6)

(4) Exercises

• Correlated Samples t-test (answers)
• One Sample, Two Samples, and Correlated t-tests (with answers)
• Correlation (answers)

(5) Detailed Presentation 

Notes 5c: Correlated Samples t-test

• Read: Notes 5c Correlated Samples t-test
• Read: Moore et al text chapter 7.
•  Critical t-values table: t-tables.pdf
• Watch and Read: Instructional Videos and Related Materials
  • Section 1: Purpose of Correlated-samples t-test  
  • Sections 2 to 5: Hypothesis Testing Steps, Hypotheses, Decision Rules, Formulas 
  • Sections 6 and 7: Computational Formula for paired t-test, Confidence Intervals 
  • Section 8: Example 1 with SPSS (SPSS starts at about 9:55 in video) 
  • Section 8: Example 2 with SPSS (SPSS starts at about 9:25 in video) 
  • Section 9: APA Style Presentation    
  • Section 10:  Individually Matching vs. Subgroup Matching (to be added) 
• Supplemental Excel file: Correlated Sample t-test 
• Supplemental Readings:
  • http://www2.chass.ncsu.edu/garson/pa765/ttest.htm
  • http://www2.sjsu.edu/faculty/gerstman/StatPrimer/Hyp-test.PDF 
  • http://www2.sjsu.edu/faculty/gerstman/StatPrimer/independ.pdf 
  • http://www2.sjsu.edu/faculty/gerstman/StatPrimer/paired.pdf 

Notes 6: Correlation Coefficient, Pearson's r

• Read: Notes 6 Correlation Coefficient, Pearson's r
• Read: Moore et al text chapters 2 and 10.
• Critical Pearson r values table: critical r  
• Critical t-values table: t-tables.pdf  
• Interpretation of Correlation Coefficients (Lovakov and Agadullina 2021 - see Table 2 Empirically Derived Thresholds, small > .12, medium > .24, and large > .41)
• Video - Correlation and Causation: English is the Cause of Death (4 minutes)
• Video Game - Guess the Correlation (play this to help you assess correlation strength via scatterplots)
• Watch and Read: Instructional Videos and Related Materials
  • *Section 1: Correlation 
  • *Section 2: Properties of Pearson's r (used SPSS to create scatter plots)   
  • *Section 3: Factors that May Alter Pearson's r   
  • *Sections 4 and 5: Correlation and Causation, Pearson r Calculation  (use of SPSS to calculate Pearson r starts 4:18 in video)
  • Section 6: Hypothesis Testing with t-ratios (Section 6, subsections a through e)  
  • Section 6: Hypothesis Testing with Critical r values (Section 6, subsection f)  
  • Section 6: Hypothesis Testing with p-values (Section 6, subsection g)
    • SPSS data files used in subsection g (note that data are fictitious):
    • Hours Studied and Statistic Grades (Google Drive file access: https://drive.google.com/file/d/1U9G2jYNqDe8PUKEC9P2rFZkKE80DzLKN/view?usp=drive_link)   
    • Academic Self-efficacy and Test Anxiety (Google Drive file access: https://drive.google.com/file/d/1FJnPLOC_8TguqDeaV5A_3wLsXbw5pV58/view?usp=drive_link)  
  • Section 6: Hypothesis Testing Exercise (Section 6, subsection h)     
  • *Section 7: Correlation Matrices  
  • Section 8: APA Style Presentation  
  • Section 9: r² - proportional reduction in error   
  • Section 10: Alternative Correlations  (to be added)
  • Scatterplot - should always examine the scatterplot between variables: Youtube example in SPSS: https://www.youtube.com/watch?v=2_PTUOQ4DbY
• Excel file showing Z score formula for finding a correlation: Z score formula for finding correlation   
• Supplemental Readings:
  • Read this: Correlation Coefficients and Scatterplots
  • http://www.wadsworth.com/psychology_d/special_features/ext/workshops/correlation.html
  • http://www2.chass.ncsu.edu/garson/pa765/correl.htm
  • http://davidmlane.com/hyperstat/A34739.html
  • http://www.wellesley.edu/Psychology/Psych205/pearson.html
  • http://www.une.edu.au/WebStat/unit_materials/c6_common_statistical_tests/test_signif_pearson.html