16-06-2014, 03:40 PM
[u]Displaying Data[/u]
Displaying Data.pptx (Size: 134.82 KB / Downloads: 14)
Tables
Help in presenting large amounts of detailed information in a small space.
A table has 5 parts:
Title
Stub
Column headings
Body
Supplementary notes or footnotes
Types of Tables
On the basis of number of variables,Tables are categorised into two:
Univariate or frequency tables
Bivariate or cross tabulations
Polyvariate/multivariate
Types of Percentages
Row percentage
Column percentage
Total percentage
Graphs
The main objective of a graph is to present data in a way that is easy to understand and interpret, and interesting to look at.
Its based entirely on the tabled data.
For interpretation, we must keep in mind the measurement scale
Histograms
A histogram consists of a series of rectangles drawn next to each other without any space between them, each representing the frequency of a category or subcategory.Their height is in proportion to frequency they represent
Bar chart
Used for displaying categorical data.
Its identical to a histogram, except that in a bar chart the rectangles representing the various are spaced.
They are used for variables measured on nominal or ordinal scales
Frequency Polygon
The frequency polygon is very similar to a histogram. A frequency polygon is drawn by joining the midpoint of each rectangle at a height commensurate with the frequency of that interval
Cumulative frequency polygon
Its drawn on the basis of cumulative frequencies. The main difference between a frequency polygon and a cumulative frequency polygon is that the former is drawn by joining the mid points of the intervals, where the latter is drawn by joining the end points of the intervals because cumulative frequencies interpret data in relation to the upper limit of an interval
The stem-and-leaf display
The stem-and-leaf is an effective, and simple way of displaying a frequency distribution. The stem-and-leaf for a frequency distribution running into 2 digits is plotted by displaying digits 0 to 9 on the left of the y-axis,representing the tens of a frequency. The figures representing the units of a frequency (i.e. the right hand figure of a 2 digit frequency) are displayed on the right of the y-axis.
The scattergram
A scattergram is extremely effective in showing visually how one variable changes in relation to a change in the other variable. Data for both variables are taken in pairs and in absolute values for each observation displayed as dots in relation to their values on both axes