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Part C: Regression analysis

The researcher is now interested in seeing if there is a linear relationship between WIL grades

and work competencies among students, using regression analysis and keeping the three

programs separate.

(Hint: WIL grades will be y variable and work competencies will be predictor variable on

iNZight. Use Subset by Program when selecting variables.)

1. Using the WILA3 data, draw the scatter plots, using work competencies as the explanatory

variable. Add the straight lines to the plots (use Add to Plot then Trend lines and curves and

Linear). Copy these graphs to your assessment. Describe what they tell you.

The Open Polytechnic of New Zealand Ltd

2. Record the values of the correlation (r) and R-squared for each of the three programs and

state the information each of these values gives you. Comment on the similarity or dissimilarity

observed.

3. From the software output, record the equation of the regression line for BOB students only.

Make a prediction for the WIL grade of a BOB student with a work competency score of 30.

• State the hypotheses in words or symbols.

Report the p-value and the confidence interval for the slope.

Ver: A1.0

4. Assuming all conditions for a valid test are met, carry out the hypothesis tests to see if there

is evidence of a relationship in the population the sample was drawn from. Note do not use

subset by Program. As part of this make sure you:

• Copy the computer output to your appendix.

Interpret the test results and make a conclusion.

Interpret the confidence interval.

(Hint: you may find exponential notation used in your output. As an example, a p-value of 4e-03

means 4 x 10-3 or 0.004.)

5. Why might you not have confidence in predicting the WIL grades of a student with a work

competency score of 50?