BIOE: Data Presentation Flashcards
• display data clearly and effectively
• summarize quantities of information
DATA PRESENTATION
• display data
• avoid distortion of data
• allow the viewer to make comparisons
• allow the reader to think what the data convey
• allows description, exploration, tabulation or decoration
• be closely related to the statistical and verbal description of the data set
DATA PRESENTATION
• describing data by the use of statements with few numbers
• presented in paragraphs or sentences
• explain results and trends, and provide contextual information
Purpose:
• to stress or emphasize significant information
Textual Presentation
Example:
• “The incidence rate of delirium following anesthesia was 11% in 2016 and 15% in 2017; no signific
Textual Presentation
Advantages:
• gives emphasis to significant data • use for few data
Disadvantages:
• data becomes incomprehensive when large quantitative data are included in paragraph
• paragraph involving many figures can be tiresome to most readers when same words are repeated many times
Textual Presentation
• data are converted into words or numbers in rows and columns
• note: data should never be put in a table if it can be described in 1-2 sentences
Consideration in table construction: • simplicity
• clarity
• directness
Tabular Presentation
Purposes:
• data checking and editing
• summarizing and presenting data
• basis, aid in graph or chart construction
Tabular Presentation
Guidelines:
• self-explanatory
• all sources are specified
• headings are specific and understandable for every column & row
• row and column totals are checked for accuracy
• cells are not left blank; enter “0” or “-”
• categories are mutually exclusive and exhaustive
Tabular Presentation
- ________ table
• single table which allows the distribution of observations across many variables of interest in a given study
• each observation is cross classified across the variables which may be quantitative or qualitative data
Purpose:
• store information with an aim of presenting detailed statistical data • facilitate generation and tabulation of smaller table
Tabular Presentation
Types:
2. _______ table
• complete except for data
• give preview of what table outputs may be expected from the study Purpose:
• help researcher clarify instrument
• help protocol reviewer & computer programmer
Tabular Presentation
Types:
2. Tables by number of variables presented
• One-way table
• Two-way table
• Multi-way table
Tabular Presentation
Advantages:
• easy to understand
• compact and concise than textual form
• presents greater detail of data than graph
• readily points out trends, comparisons and interrelations • facilitates analysis of categories of given variable
Tabular Presentation
Disadvantages:
• too many rows and columns could make it difficult for the reader to understand the data
• requires more time to construct
Tabular Presentation
• pictorial representations of certain quantities plotted with reference to a
set of axes
• graphs simplify complex information by using images and emphasizing data patterns or trends
• useful for summarizing, explaining, or exploring quantitative data
• present both large and small amounts of data
Graphical presentation
Uses:
• visually summarize the variables (data set is large) • emphasize particular statement about data set
• enhance readability
• appeal the visual memory
Graphical presentation
Guidelines:
• include, below the figure, a title providing all relevant information • be referred to as figures in the text
• identify figure axes by the variables under analysis
• quote the source which provided the data, if required
• demonstrate the scale being used
• be self-explanatory
Graphical presentation
Types:
• pie chart
• bar graph
• component bar graph • line graph
• histogram
• frequency polygon
• stem-and-leaf plot
• box plot
• scatter plot
Graphical presentation
• circles subdivided into a number of slices
• area of each slice represents the relative proportion data points falling into given category
• usetoshowhowa whole is divided into its component parts which could be breakdowns of groups or totals
Pie chart
• consists of bars of the same sizes
• horizontal or vertical with gaps between to emphasize discontinuities
• also know as _____________________
• types:
• simple bar graph
• multiple bar graph
• height of bars/rectangles: quantity of variables
Bar graph
Guidelines:
• height of bars should be proportional to the frequencies or rates of categories
• width of bars should be equal
• percentages & rates must be used when total number of observations for
the groups are not uniform
• when percentages are used, the sum of the heights of all the bars must be equal to 100%
• to make them more appealing, bars are either colored or shaded in different ways
Bar graph
• plot of dots joined with lines over some period of time in sequential series
• _________________
• horizontal axis: time series • vertical axis: variable values
Line graph
• bar is used to depict number or relative frequencies of data points falling into the given class
• bars are drawn over the true limits of the classes, no gaps exist in between
• horizontal axis: continuous quantitative
• vertical axis: number of relative frequencies
• preferred for grouped interval data
Histogram
• similar to histogram except that:
• frequencies are plotted against the corresponding midpoints of the classes
• adjacent points are joined with lines and the plot is tied down to the horizontal axis resulting in multi-sided polygon
Frequency polygon
• primarily for small set of data
• provides rank-ordered lists and its easier to restore the original value of the observation
• lines gives more information than bars in histogram
• used to show the actual data value instead of using bars to represent the height of an interval
Stem-and-leaf plot
• shows description of a large quantitative data
• include center, spread, shape, tail length, and outlying data points
• can be presented horizontal or vertical
• height of rectangle is arbitrary and has no specific meaning
• used for comparing the distributions of several variables or the distribution of a single variable in several groups on the same scale
Box plot
• shows the relationship between two quantitative variables
• gives rough estimate of the type and degree of correlation between the variables
Scatter plot
Advantages:
• main feature & implications of the body of data can be grasped at a glance
• more attractive & appealing to a wider range of readers
• simplifies concepts that would otherwise have been expressed in so
many words
• shows trends & patterns of a large set of data
• comparisons could be made more striking
• can be readily clarify data
Graphical presentation
Disadvantages:
• cannot show as many sets of facts
• can only show approximate values
• require more time to construct
• may be used to misinterpret results
Graphical presentation
