ST3003 Assessment

ST3003 Assessment

The Normal Distribution and Confidence Intervals

Part 1 — Confidence Intervals in Research

For this section, refer to the following article from the Walden Library: Check tips on how to do your Nursing Assignment.

References

Siamisang, K., Kebadiretse, D., Tjirare, L. T., Muyela, C., Gare, K., & Masupe, T. (2022). Prevalence and predictors of depression, anxiety and stress among frontline healthcare workers at COVID-19 isolation sites in Gaborone, Botswana. PLoS ONE, 17(8), e0273052. https://doi.org/10.1371/journal.pone.0273052

All articles are available in full text in the Walden Library, which you may search by title or DOI. Be sure to provide an explanation for each of your answers and include supporting evidence from the text and/or Learning Resources.

ST3003 Assessment

Write responses to address the following in paragraph form by inserting your answers directly beneath the questions.

Table 3 of the journal article displays the number of health care workers who report various levels of depression, anxiety, and stress. These numbers are presented as the number of workers as well as the percent of the total (447). Confidence intervals are given for each percentage value. Choose ONE level of either depression, anxiety, or stress (e.g., normal depression) to use to address the following questions:

1. Show how the given percentage was derived based on the sample data.
2. Write 1–2 sentences explaining how the confidence interval would be interpreted.
3. Based on this interval, provide one value that could be considered reasonable as the population proportion and one that would not be considered reasonable as the true population proportion. Fully explain your reasoning.
4. If a subsequent study was completed that increased the sample size to 1,000 participants, explain one change you would expect to see in the confidence intervals. Explain why you feel this change would occur.

Table 1 of this journal article provides a breakdown of characteristics of the 447 participants in this study. The number of participants is given, followed by the percentage in ().

1. Provide one reason you believe a confidence interval was not presented for this data.

ST3003 Assessment

Part 2 — Using the Normal Distribution

The following should be based on the data set you created from the larger BODY DATA (ST3001) data set complete the following table:

	Smokers	Nonsmokers
Mean
Standard deviation
Sample size (n)

 

Replace the questions below with your response to the following:

Use the table above to answer the following questions based on your individual data. For each question, write a 1-sentence explanation about how Excel was used to assist you in your computations.

1. Find the percent of smokers expected to have a BMI of greater than 25 (overweight).
2. Find the percent of nonsmokers expected to have a BMI of less than 18.5 (underweight).
3. A normal BMI range is between 18.5 and 24.9. What percent of smokers are expected to be within this range? What percent of nonsmokers are expected to be within this range?
4. A researcher is interested in which BMI represents the 90^th percentile (90% are at this BMI level or lower). What BMI score represents the 90^th percentile cut-off rate?

ST3003 Assessment

Part 3 — Creating Confidence Intervals

Use the table above when addressing the following.

Complete the following table:

Group	90% confidence interval	95% confidence interval	99% confidence interval
Smokers
Nonsmokers

 

Replace the questions below with your response to the following:

1. As the level of confidence increases, what happens to the width of the confidence interval? Does it increase or decrease? Explain one reason why this would happen.
2. Using the 95% confidence interval, compare the BMI of smokers vs. nonsmokers. Write a 2–3 sentence paragraph explaining whether these intervals overlap or not. What does that indicate about the differences in BMI between the two groups?
3. In 1–2 sentences, explain the following: What is one situation in which you as a researcher might choose a 99% confidence interval? A 90% interval? Fully justify your choices.

References

Include appropriately formatted references to scholarly sources to support the statements made in your report. Please refer to the Academic Writing Expectations Checklist for more information.