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Week 8 ETEC 668 Quantitative Research in Educational Technology Dr. Seungoh Paek March 5, 2014
Using Inferential Statistics Linear Regression
How Inference Works • A representative sample of the population is chosen. • A test is given, means are computed and compared • A conclusion is reached as to whether the scores are statistically significant • Based on the results of the sample, an inference is made about the population.
What is Prediction All About? • Correlations can be used as a basis for the prediction of the value of one variable from the value of another • Correlation can be determined by using a set of previously collected data (such as data on variables X and Y) • calculate how correlated these variables are with one another • use that correlation and the knowledge of X to predict Y with a new set of data
The Logic of Prediction • Prediction is an activity that computes future outcomes from present ones • What if you wanted to predict college GPA based on high school GPA?
Regression Line • Regression line – reflects our best guess as to what score on the Y variable would be predicted by the X variable. • Also known as the “line of best fit.”
Error in Prediction • Prediction is rarely perfect…
Drawing the World’s Best Line • Linear Regression Formula • Y=bX + a • Y = dependent variable • the predicted score or criterion • X = independent variable • the score being used as the predictor • b = the slope • direction of the line • a = the intercept • point at which the line crosses the y-axis
Let’s try predicting… • Let’s use PSPP to compute the regression line in predicting Y from X • We’ll use the number of hours of training to predict how severe injuries will be if someone is injured playing football
Using the Computer • SPSS and Linear Regression
SPSS Output • What does it all mean? Y = -.13 X + 6.85
Data Analysis Procedures February 27, 2013
Where are we now? • Identified a problem focus • Outlined literature review • Stated research questions • Research questions provide the basis for planning research study – design, materials, data analysis • Determined research design • Experimental, survey, correlational, descriptive • Determined methods • Subjects, materials, instruments, procedures • Next, identify data analysis procedures
Data Analysis Procedures • Excited? Apprehensive? No worries! • If you’ve done a good job of the preceding 5 steps, this should be straightforward & easy • Clear research questions & design leads to stats analysis required • Work with a stats expert – identify one for your dissertation committee • Your task –have practitioner’s understanding of appropriate analyses, how to perform PSPP analyses & how to interpret results
Can meaningful learning be enhanced by using a computer to personalize math word problems for each student?