Research Methods II
Type I error
the rejection of a true null hypothesis
Type II error
the acceptance of a false null hypothesis
a statement of no relationship between variables; rejected when an observed statistic appears unlikely under the null hypothesis.
A theoretical distribution that can be specified for any statistic that can be computed for samples from a population
One Tailed Test
a statistical test where extreme results leading to rejection of the null hypothesis can be located at either tail
Two Tailed Test
A statistical test where extreme results leading to rejection of null hypothesis will be located at both left and right tails
What can happen when you control for a third variable in a bivariate relationship?
2. The correlation between X and Y reduces dramatically (Either there is spuriousness or Z is intervening)
3. The relationship between X and Y changes but does not disappear (then Z is a conditional variable)
Issues in Questionnaire Construction
What do you want to know? What do you expect respondents to know?
Question Content (Fact or Opinion, wording, provide middle alternatives)
Question Type: Closed vs Open-ended
Response Format for Closed-ended
What to consider when evaluating a Poll (1)
Topic - is it something people know about?
Screen for non-attitudes – Did the organization give respondents middle
Question wording -Did the organization give you the question wordings?
Question Order: Questions can be placed to lead respondents in certain ways
What to consider when evaluating a Poll (2)
Sample definitions - Probability sample? From what population?
Sub-sample sizes and error margins
What happens if certain demographics are pulled
out? (error margin increases)
Who sponsored the poll?
What's the spin?
Advantages of Secondary Analysis
May be the only source
You can replicate/triangulate someone else's research with your own
Disadvantages of Secondary Analysis
May only approximate the data you want
May have hidden biases
Sometimes access is a problem
Advantages of Interviewer-Administered Questionnaires
Higher response rate
Can probe and clarify
Disadvantages of Interviewer-Administered Questionnaires
Possible interviewer bias
Advantages of Self-Administered Questionnaires
No interviewer bias
Disadvantages of Self-Administered Questionnaires
Lower Response Rate
Requires simple questions and answers
Nobody there to clarify/probe
Takes time (opportunities for outside phenomena to interfere)
Research Methods II
For GSPM Research Methods