Learning Activity 8:
Quantitative Data Analysis
Central Tendency, Variability
Descriptive - Univariate Statistics
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“To behold is to look beyond the fact; to observe, to go beyond the observation.
Look at the world of people, and you will be overwhelmed by what you see.
But select from that mass of humanity a well-chosen few, and observe them with
insight, and they will tell you more than all the multitudes together.”
- Leedy and Ormrod (2001).
Practical Research: Planning & Design, (p. 191).
“Descriptive or univariate statistics are used to describe a particular
sample or a particular individual within a sample. The data are limited to
describing only one variable, group, or individual. Any conclusions that
are made cannot be extended to anyone outside that particular sample.”
- Talbot, L. (1995).
Principles and Practice of Nursing Research, (p. 318).
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Overview
Descriptive statistics provide a visual representation of data in the form of graphs, plots, spreads, frequency distributions, and so on. Without statistical analysis, the copious amount of numerical data collected in quantitative studies would be overwhelming and meaningless. Data needs to be described and synthesized to have meaning. Descriptive statistics is the common method used by researchers to organize and summarize numerical data gathered from populations and samples.
Descriptive statistics are generally divided into four functional groups. The first includes measures to condense data; the second is the measures of central tendency; the third is measures of variability and the fourth is measures of relationships.
Measures to condense data include frequency distributions, frequency counts, graphic presentations and percentages. (Nieswiadomy, 2002).
Measures of Central Tendency describe the average or common value for a group of data. This includes measurements of mode, median and mean, which reduces the frequency distributions to a common, single numbers.
Measures of Variability or Spread show what the spread is like within a distribution of values. Common measures of variability include the range, interquartile percentile, standard deviation and variance.
Measures of Relationship are concerned with the correlation (relationship) of variables and contingency tables.
Ends In View
This learning activity is intended to provide learners with the opportunity to:
1. Explore the nature of quantitative data.
2. Understand the rationale for descriptive data analysis.
3. Review the process of qualitative data collection.
4. Recognize the utility of applying nominal, ordinal, interval, and ratio measurement.
5. Explore the process of visually reporting descriptive qualitative data.
6. Practice descriptive quantitative data analysis using a computer software program.
7. Explore the process of univariate quantitative data collection and analysis.
8. Recognize the utility of performing frequency distributions, central tendency, spreads, distribution and variability on quantitative data.
9. Critique the quantitative data collection and analysis process described in a select research study.
In Preparation
1.Read: Trochim, W. (2002). Descriptive Statistics. Social Research Methods.
2.Read: The content of this entire learning activity including notes and definitions.
3.Research Text: If you have a Research textbook such as LoBiondo-Wood or Gillies, read the chapter on Descriptive Statistics.
Assignment 2: Complete the assigned Worksheet 1: Central Tendency and Variability (will be given out in class, or can be downloaded from the Kwantlen protected site on the campus Online Courses site). Save your work and submit with the four worksheets to follow in the next four learning activities. NOTE This is NOT the worksheet in your course materials - that one is for practice.
In Practice
1.Participate in class discussion related to the process of quantitative descriptive data collection and analysis (review Figure 8 at end of learning activity).
2.In pairs, complete Worksheet No. 7 noticing the various methods of descriptive data analysis.
3.Explore the use of visual displays in the process of descriptive data analysis.
In Lab - Introduction to Descriptive Statistics (may use Excel Software Program or Online Tools)
1. Attend lab to familiarize yourself with the Excel software and functions.
2.Review the following online orientation materials to further understand the application and process of using the Excel software for statistical analysis:
3.View the Online Microsoft Tour "Excel 2000 Tour"
4. Refer to the Online Tutorial: "Excel for Introductory Data Analysis" by Hossein Arsham.
5.Read: University of Alberta (2002). Doing Statistics with Excel 2000.
6. Begin to work with quantitative data by performing descriptive data analysis using the Excel software as directed during lab session.
In Reflection
1.Reflect on your comfort level with using the Excel software for statistical analysis.
2. How does descriptive analysis add depth and understanding to nursing research and evidenced based practice?
References
Leedy and Ormrod (2001). Practical research: Planning & design. Upper Saddle River,
NJ: Merrill Prentice Hall.
LoBiondo, G. & Haber, J. (2005). Nursing nesearch in Canada: Methods, critical appraisal, & utilization. (1sth ed.) Toronto: Elsevier.,
Nieswiadomy, R. (2002). Foundations of nursing research. Stamford, CT: Appleton & Lange.
Talbot, L. (1995). Principles and practice of nursing research, Toronto: Mosby.
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Welcome to NRSG 4120!
Figure 8: Descriptive Statistics
LA#8: Practice Worksheet
LA#8: Handout
VISUAL RESOURCES
Central Tendency (cheatsheet)
Central Tendency (Video)
Mean, Median, Mode (video)
Being Normal in a Z Score World(Video)
Measures of Central Tendency
Standard Deviation Graph
Levels of Measurement Overview
POWERPOINT RESOURCES
Central Tendency Dispersion(PPT, nice intro)
Descriptive Statistics(PPT, excellent!)
Measures of Variability with Quiz (PPT on SD, variance)
Describing Data (PPT)
REVIEW RESOURCES
Levels of Measurement Review
Measures of Central Tendency with some MS Excel Tips
Standard Deviations in Excel
Mean and SD in Excel Exercise
Standard Deviation Applet
Central Tendency Quiz (do at computer)
Range Demo Questions
Range Practice Questions
Downloading Files
Most files are in PDF, DOC, or RTF format. If you have trouble viewing them online,
try right-clicking on the link, and select "Save Target as". Remember which folder you saved the file in.
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