PSY 325 FINAL EXAM

Essay 1. A group of researchers conducted an experiment to
determine which vaccine is more effective for preventing getting the
flu. They tested two different types of vaccines: a shot and a nasal
spray. To test the effectiveness, 1000 participants were randomly
selected with 500 people getting the shot and 500 the nasal spray. Of
the 500 people were treated with the shot, 80 developed the flu and 420
did not. Of the people who were treated with the nasal spray, 120 people
developed the flu and 380 did not. The level of significance was set at
.05. The proportion of people who were treated with the shot who
developed the flu = .16, and the proportion of the people who were
treated with the nasal spray was .24. The calculated p value = .0008.

For this essay, describe the statistical approaches (e.g., identify
the hypotheses and research methods) used in this excerpt from a
research study.  Interpret the statistical results and examine the
limitations of the statistical methods.  Finally, evaluate the research
study as a whole and apply what you have learned about hypothesis
testing and inferential statistics by discussing how you might conduct a
follow-up study.

Your essay must address the following points:

Describe the research question for this experiment.
What were the null and alternative hypotheses? Were the results of this test statistically significant? If so, why were they significant? Would the researchers reject or fail to reject the null hypothesis? Do the results provide sufficient evidence to support the alternative hypothesis? Was the sample appropriate for this study?  Explain your answer. What are some possible limitations to this study? Discuss how you would conduct a follow up study to this one. Explain your answer. Describe the difference between practical and statistical significance.

Essay 2. A researcher has investigated the relationship between IQ and grade point average (GPA) and found the correlation to be .75.

For this essay, critique the results and interpretation of a correlational study.

Evaluate the correlational result and identify the strength of the correlation. Examine the assumptions and limitations of the possible connection between the researcher’s chosen variables.   Identify and describe other statistical tests that could be used to study this relationship.

Your essay response must address the following questions:

How strong is this correlation?
Is this a positive or negative correlation? What does this correlation mean? Does this correlation imply that individuals with high Intelligence Quotients (IQ) have high Grade Point Averages (GPA)?   Does this correlation provide evidence that high IQ causes GPA to go higher?
What other variables might be influencing this relationship? What is the connection between correlation and causation? What are some of the factors that affect the size of this correlation? Is correlation a good test for predicting GPA? 
 If not, what statistical tests should a researcher use, and why?

Essay 3. A researcher has recorded the reaction times of 20
individuals on a memory assessment. The following table indicates the
individual times:

 2.2

 4.7

 7.3

 4.1

 9.5

 15.2

 4.3

 9.5

 2.7

 3.1

 9.2

 2.9

 8.2

 7.6

 3.5

 2.5

 9.3

 4.8

 8.5

 8.1

In this essay, demonstrate your ability to organize data into
meaningful sets, calculate basic descriptive statistics, interpret the
results, and evaluate the effects of outliers and changes in the
variables.  You may use Excel, one of the many free online descriptive
statistics calculators, or calculate the values by hand and/or with a
calculator. 

Next, separate the data into two groups of 10; one group will be the
lower reaction times, and the second group will be the higher reaction
times.  Then, address the following points in your essay response:

Calculate the sum, mean, mode, median, standard deviation, range, skew, and kurtosis for each group. How do the two groups differ?   Are there any outliers in either data group? What effect does an outlier have on a sample?

Lastly, double each sample by repeating the same 10 data points in
each group.  You will have a total of 20 data points for each group.
After completing this, address the following in your essay response:

Calculate the following for the new data groups: sum, mean, mode, median, standard deviation, range, skew, and kurtosis. Did any of the values change? How does sample size affect those values?

Part B: Research Study CritiqueIn this second portion of the Final Exam, you will identify and
critically evaluate a quantitative research article based on a social
science topic.  Your selected article must include a research
question(s) and/or hypothesis(es) and utilize statistical analyses
covered in the course. The article must be peer-reviewed and published
within the last 10 years.

In the body of your critique, describe the statistical approaches used,
the variables included, the hypothesis(es) proposed, and the
interpretation of the results.  In your conclusion, suggest other
statistical approaches that could have been used and, if appropriate,
suggest alternative interpretations of the results.  This process will
allow you to apply the concepts learned throughout the course in the
interpretation of actual scientific research. Your critique must include
the following sections:

Introduction: This section will include a
general introduction of the quantitative study from a peer-reviewed
source published within the last 10 years.  The research questions
and/or hypothesis(es) as well as the purpose of the study should be
clearly defined. Methods: Describe and evaluate the procedures
and methods of data collection, measures/instruments used, the
participants and how they were selected, and the statistical techniques
used. Results: In this section describe and critique the results presented in the study. Discussion: Discuss and evaluate the efficacy
of the results presented in the study.  Address, the strengths,
weaknesses, and limitations of the study, and suggest future research
directions.  Include additional forms of statistical analyses as part of
the suggestions for future research.

The Research Study Critique:

Must be three to four double-spaced pages in length (excluding
title and reference pages) and formatted according to APA style as
outlined in the Ashford Writing Center.  Use 12-point font, with 1-inch
margins.  Must use the sections and headings described above.   Must address the article with critical thought by examining,
reflecting, and evaluating the article from an objective viewpoint and
by using facts to support your argument. Refer to the Critical Thinking
Community website for further assistance. Must end with a conclusion that summarizes your critical evaluation. Must use one quantitative research study from a peer-reviewed source that was published within the last 10 years. Must properly cite the source article in APA style as outlined in the Ashford Writing Center. Must include a separate reference page, formatted according to APA style as outlined in the Ashford Writing Center.