Introduction-to-Statistics-and-Quantitative-Research-Methods
Introduction-to-Statistics-and-Quantitative-Research-Methods
Introduction-to-Statistics-and-Quantitative-Research-Methods
- No tags were found...
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Why square deviations?To calculate variance, the meanof a group of scores issubtracted from each score <strong>to</strong>give a group of ‘deviations’.• When we take the average ofthe deviation scores, the meanis calculated as the average,<strong>and</strong> the deviance scores <strong>to</strong>talzero (positive <strong>and</strong> negativescores cancel).• If you first square the deviationscores <strong>and</strong> then add them, youavoid this problem.• The average of these squareddeviation scores is called thevariance.X=individual scoreM=mean of all scoresn= number of scoresExample:80 mean score5 scoresIndividual scores: 90, 90, 70, 70, 80.Sum of (90-80), (90-80), (70-80), (70-80), (80-80)= 0NEED TO SQUARE!(90-80) 2 + (90-80) 2 +(70-80) 2 +(70-80) 2 + (80-80) 2 =100+100+100+100+0=400Variance=100
Change language