1. Calculating & Reporting Healthcare Statistics
Second Edition
Chapter 11
Presentation of Data

2. Types of Data - Categorical
Four types or scales of measurement of categorical data
Nominal
Ordinal
Ratio
Interval
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3. Types of Data - Categorical
Nominal Data
Lowest level of measurement
“Nominal” means “pertaining to a name”
Observations are organized into categories
There is no recognition of order within these categories
For example
True/false
Male/female
Types of insurance carriers
Patient occupations
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4. Types of Data - Categorical
Nominal Data
Numbers may be used to represent categories
For example
Males may be listed as 1, female as 2
Persons may be grouped according to blood type, where 1 represents type A; 2, type B; 3, type AB; and 4, type 0
The sequence of the values is not important. The numbers simply serve as labels for the some piece of information
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5. Types of Data - Categorical
Ordinal Data
Values are in ordered categories
“Ordinal” means “to put something in order”
On the ordinal scale, the order of the numbers is meaningful, not the number itself
The intervals or distance between categories are not necessarily equal
For example
Head injuries may be classified according to level of severity, where 4 is fatal; 3, severe; 2, moderate; and 1, minor
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6. Types of Data - Categorical
Ordinal Data
A natural order exists among the groupings
The largest number representing the most serious level of injury
The order could be revised
Intervals between ordered categories are not assumed to be equal
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7. Types of Data - Categorical
Interval Data
Include units of equal size
There is no zero point
For example
Temperature in Fahrenheit degrees
The intervals between the values are the same
The most important characteristic is that the intervals between values are equal
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8. Types of Data - Categorical
Ratio Data
The highest level of measurement
There is a defined unit of measure
There is a real zero point
The intervals between successive values are equal
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9. Types of Data - Categorical
Ratio Data
May be displayed by units of equal size placed on a scale starting with zero and thus can be manipulated mathematically, such as 0, 5, 10, 15, and 20
For example
Age
The difference between two years would be the same (the difference between age 1 and 2 is 1 year; the difference between age 55 and 56 is one year, and so on)
There is a “zero point” in that zero would mean an absence of age or birth
Someone who is 100 years old is twice as old as someone who is 50 years old
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10. Types of Data Numerical Data Two types of numerical statistical data
Discrete data
Continuous data
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11. Types of Data – Numerical
Discrete data
Discrete data are finite numbers
They can have only specified values
For example
The number of children in a family
A family can have two or three children but cannot have 2.25 or 3.5 children
The numbers represent actual measurable quantities rather than labels
Other examples
The number of motor vehicle accidents in a particular community
The number of times a woman has given birth
The number of new cases of cancer cases in your state within the past five years
The number of beds available in your hospital
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12. Types of Data – Numerical
Discrete Data
A natural order exists among the possible data values
In the example of the number of times a woman has given birth, a larger number indicates that she has had more children
the difference between one and two births is the same as the difference between four and five
the number of births is restricted to whole numbers (a woman cannot give birth 2.3 times)
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13. Types of Data – Numerical
Continuous Data
A measure of quantity will usually be continuous
It can take on a fractional value
For example
A patient’s temperature may be º F
Height - One could say that someone is approximately 6 feet tall, refine it to 5 feet 10 inches, and refine it still further to 5 feet 10 ½ inches
Age - You may have been 20 years old on your last birthday, but your are 20 plus some part of another year
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14. Types of Data – Numerical
Continuous Data
The only limiting factor for a continuous observation is the degree of accuracy
For analysis, continuous data often are converted to a range that acts as a category
For example
Age can be categorized in ranges (0–20, 21–40, and so on)
Measurements on the interval and ratio scales are can be grouped
Interval and ratio variables are continuous
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15. Data Display
Data is generally presented in the forma of a table or graph and charts
Tables are used for summarizing data
Graphs can present data for quick visualization of relationships
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16. Data Display Advantages to using tables
More information can be presented
Exact values can be entered to retain precision
Supportive details can be provided
Less work and fewer costs required in the preparation
Flexibility is maintained without distortion of data
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17. Data Display Advantages to using graphs and charts
They get the audience’s attention
Easy to understand
Bring out hidden facts
Vividly display trends or comparison
A picture is worth a thousand words
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18. Data Display
Tables
An orderly arrangement of values that groups data into rows and columns
Almost any type of quantitative information can be grouped into tables
Columns allow you to read data up and down while rows allow you to read data across
Columns and rows should be labeled
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19. Data Display Tables - essential components Title Stub heading
Must explain as simply as possible what is contained in the table
Stub heading
The title or heading of the first column
Column headings
The headings or titles for the columns
Stubs
The categories (the left-hand column of a table)
Cells
The information formed by intersecting columns and rows
Source footnote
The source for any data should be identified in a footnote
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20. Data Display Frequency Distribution Tables
Shows the values that a variable can take and the number of observations associated with each value
A variable is a characteristic or property that may take on different values
For example
Third party payors
Discharge service
Admission day
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21. Data Display Frequency Distribution Tables
Constructing A Frequency Distribution Table
For example
A study for our Utilization Review Committee
They would be interested in knowing the admission days for patients
List the days of the week, Sunday through Saturday
Then enter the observations, or number of patients admitted on the corresponding day of the week
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22. Data Display
Graphs
Graphs of various types are the best means for presenting data for quick visualization of relationships
They often supply a lesser degree of detail than tables
Data presented in a graph can be helpful in displaying statistics in a concise manner
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23. Data Display Graphs Should be easy to read Simple in content
Correctly labeled
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24. Data Display Graphs – guidelines for creating graphs Title
Must relate what the graph shows as simply as possible
Legend or key
Use when including two or more variables on the same graph
Categories
Should be natural
The vertical axis should always start with zero
The scale of values for the x-axis reads from the lowest value on the left to the highest on the right
The scale of values for the y-axis extends from the lowest value at the bottom of the graph to the highest at the top
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25. Data Display Graphs – guidelines for creating graphs Scale captions
Placed on both axes to identify the values clearly
These are simply titles placed on each axis to identify the values
Graphs should emphasize the horizontal
It is easier for the eye to read along the horizontal axis from left to right
Graphs should be greater in length than height
A guideline is to follow the three-quarter-high rule
This rule states that the height (y-axis) of the graph should be three-fourths the length (x-axis) of the graph
Source footnote
The exact reference to an outside source should be given
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26. Data Display Bar Graphs Also called bar charts
Appropriate for displaying categorical data
Simplest bar graph is a one-variable bar graph
The various categories of observations are presented along a horizontal, or x-axis
The vertical, or y-axis, displays the frequency of the data
Data representing frequencies, proportions, or percentages of categories are often displayed using bar graphs
A grouped bar chart is used to display information from tables containing two or three variables
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27. Data Display Pie Charts
A method of displaying data as component parts of a whole
A circle is divided into sections, like wedges or slices
These represent percentages of the total
(100 percent)
Data must be converted into percentages
Pie chart wedges may be shaded or colored to help differentiate the sections
Additionally, they can be cut out of the pie to help emphasize a percentage
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28. Data Display Line Graphs Used to show data over time For example
Days, weeks, months, or years
The x-axis shows the time period
The y-axis show the values of the variables
Consists of a line connecting a series of points on an arithmetic scale
Also allow for several variables to be plotted
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29. Data Display Histograms
A representation that is used to display frequency distributions for continuous numerical data (interval or ratio data)
Difference from bar graphs
Bar graphs display data that fall into categories
Histograms illustrate frequency distribution of continuous variables
Histograms are created from frequency tables
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30. Data Display Frequency Polygon May be used instead of a histogram
It is similar to a histogram in that it is a graph depicting frequency of continuous data, but, a frequency polygon is in line form instead of bar form
An advantage is that several can be placed on the same graph to make comparisons
Uses the same axes as the histogram, that is the x-axis displays the scale of the variable and the y-axis displays the frequency
A dot is placed at the midpoint of the class interval or frequency
These dots are then connected by a line that is drawn from one point to the next
Because the x-axis represents the entire frequency distribution, the line starts at zero cases and is drawn from the last frequency to the y-axis to end with zero
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31. Data Display Pictogram
An attractive alternative type of bar graph in that it uses pictures to show the frequency of the data
For example
If you wanted to show the number of individuals you can use stick people
Can be very entertaining
Can catch the attention of your audience
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32. Data Display Scatter Diagram Also called scattergram, or scatter plot
The relationship between two numerical variables is shown graphically
Used to determine if there is a correlation, or a relationship, between two characteristics
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33. Data Display Scatter Diagram
Correlation implies that as one variable changes, the other also changes
This does not always mean that there is a cause and effect relationship between two variables since there may be other variables that could cause the change
If the two characteristics are somehow related, the pattern of points will show tight clustering in a certain direction
The closer the points look like a line in appearance, the more the two characteristics are likely to be correlated
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34. Data Display Scatter Diagram
The slope of the line can be positive or negative
Positive = Small values of the x-axis correspond to small values of the y-axis and large values of the x-axis correspond to large values of the y-axis
There is said to be a positive linear relationship
Negative = Small values of the x-axis correspond to large values of the y-axis and large values of the x-axis correspond to small values of the y-axis
There is said to be a negative linear relationship
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35. Data Display
Before deciding to use a table or graph decide who will be reading the material
What detail is needed?
You may decide to create tables, graphs as well as narrative discussion to report to help people under the data
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36. Data Display When preparing reports Be objective
Report positive and negative points
Use bias-free language
Be concise and strive for clarity
Proofread your document
Review your grammatical skills
Write in the style of your workplace
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