week 8 etec 668 quantitative research in educational technology
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Week 8 ETEC 668 Quantitative Research in Educational Technology
Dr. Seungoh PaekMarch 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?
Scatter Plot
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.”
Prediction of Y given X = 3.0
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
Variable Definition
Training (X) # of hours per week of strength training
Injuries (Y) Severity of injuries on a scale of 1 to 10
Using the Computer
SPSS and Linear Regression
SPSS Output
What does it all mean?
Y = -.13 X + 6.85
Scatterplot
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?
Common Statistical Analysis Used in Ed Tech Research
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