PSY 550 Midterm Exam 2
PSY 550 Midterm Answers
Compare and contrast the following terms: (a) test-retest reliability with inter-rater
reliability, (b) content validity with both predictive validity and construct validity, and (c)
internal validity with external validity.
Test-retest reliab...
Compare and contrast the following terms: (a) test-retest reliability with inter-rater
reliability, (b) content validity with both predictive validity and construct validity, and (c)
internal validity with external validity.
Test-retest reliability and Inter-rater reliability:
Test-retest reliability measures the reliability of a test overtime and measures its consistency. For
example, if we gave the same test twice to the same people, but at a different time, we could see
if the scores are the same. We could test someone on a Tuesday and give the same test again on a
Thursday. From there, we could correlate the test scores to one another. Inter-rater reliability is
when we are looking at similarities in rating behaviors. This is when two or more raters view the
same exact behavior and are in agreement with what the viewed. Both test-retest reliability and
inter-rater reliability are forms of reliability. They both measure how stable a measure is over a
period of time.
Content validity and both Predictive validity and Construct validity:
Content validity is when we determine is the correct item or test was used. For example, we are
looking at if the test properly measures what we intended it to measure. This is different than
both construct validity and predictive validity. Construct validity is whether the scale that was
used in the test measures the construct correctly. While predictive validity is determining which
scores obtained by a certain measurement predict the outcome that it should be predicting.
Content validity, predictive validity, and construct validity are all measuring the validity of a
particular measurement.
Internal validity and External validity:
Internal validity is the extent that we can manipulate a variable and cause a change to a
dependent measure. If we have more control over a study, we have more internal validity.
Internal validity also refers to the extent of where the experiment or study is free from errors. If
any differences occur within the experiments, they are due to the independent variable and
nothing else within the study. External validity is when an experiment or study can be related
back to the world. External validity is applying the results outside the context of the study. It is
when we can generalize results of the study to other people, times, and/or situations.
Use Stevens’ model of measurement scales to answer these questions:
1. What type of scale is used when the variable is social class? Explain.
, 2. What type of scale is used when the variable studied is a Top 40 list of popular
songs? Explain.
3. What type of scale is used when the variable studied is intelligence scores (for
example, on the Stanford-Binet-R)? Explain.
4. What type of scale is used when the variables studied are low and normal birth
weights of newborns? Explain.
The scale used to explain social class would be nominal. When talking about social classes, the
different classes are categorized, "upper class", "middle class", "lower middle class", and
"working class". While they are categorized, the categories do not imply that one is better than
the other.
The scale to explain the top 40 list of popular songs would be on the ordinal scale. This is
because the songs are being ranked in order and a number is being assigned to it. By looking at
this data, we would be able to see that #32 is higher than #45.
For studying intelligence scores, we would use an interval scale. This is because there are equal
differences among the numbers on the scale. They represent equal differences in the intelligence
score. In this scale, there is no fixed zero point.
When variables studied are low and normal birth rates of newborns, we would use the ratio scale.
On this scale, there is a fixed zero point. Weight is one of the few variables that does have a zero
point.
Define and describe the six steps of the scientific method. Give an example of each step.
The six steps of the scientific method:
1. Identify a problem: To first start the scientific method, we have to choose what our
problem is and what to investigate. In this step we start to think about how to get answers
to what we are trying to find. Typically, in psychology, we are trying to investigate
problems related to human or animal behavior.
2. Develop a research plan: Once we understand what we are going to study and we have a
hypothesis, we can start to develop a research plan and how we are going to test our
variables. In this step, we also need to identify our participants, evaluate ethics and gain
approval, and select a research strategy.
3. Conduct the study: Using the plan that we developed in the previous plan, we put it into
action. While the research is being conducted, data is being measured and recorded.
4. Analyze and evaluate the data: This is where we are able to review our data and
understand what it means to our hypothesis. We summarize the results and data and
analyze to give it value to our research.
5. Communicate the results: This is when we show our results in a form of communication.
This could be in a written study, an oral presentation, or in a poster. This is also when
APA guidelines are followed to help with formatting.
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