Graphical Presentation Dr. Laila Mohamed Nofal Professor of Biostatistics High Institute of Public Health University of Alexandria
Graphical Presentation Graphical presentation is the use of a graph to show the distribution of data. Why ? • Attract the reader’s attention • A graph or diagram, provides an easily understood picture of the data. A suitable diagram is easier to grasp and leaves a more permanent impression of the main features of the data • To compare two or more distributions.
There are many varieties of graphs. The use of a particular type depends on: Type of data (quantitative continuous or discrete or qualitative) Type of table (simple or complex) Graphical Presentation
Line Graph = Trend Line • One quantitative variable & Time. • Time may be years, months, weeks, days, hours…) • No frequency distribution. • May be one or more quantitative variables bytime.
The Line Graph Example:
The Line Graph Figure (1) Crude birth rate of Country X 1997-2001
Histogram • For quantitative continuous variables • S.F.D.T only
Example: Age in Years Figure (2): Distribution of patients by age in Hospital X, 2011
Frequency Polygon • Quantitative continuous variable • SFDT or Complex FDT
Frequency Polygon • SFDT • Points are joined by straight line
Frequency Polygon • Complex FDT • Points are joined by straight line
Example: Frequency Polygon
Figure (3): Distribution of patients by age and sex in Hospital X, 2012