DISPLAYING DATA DIAGRAMMATICALLY

The Aim By the end of this lecture, the students will be aware of graphical representation of data and by using SPSS 2

The Goals To count the intended use of shapes in reporting. To count the number of basic features that must be included in graphics. To count the basic chart types and explain the features. To select the appropriate graphics about data: –If one variable is present –If many variables are present –If numerical variable is present –If categorical variable is present To do basic graphics by using SPSS. Able to determine the direction of the frequency distribution. 3

Use of Figures Using reasons 1.(Evidence) The feature that is the evidence to support the conclusion. ie: Electron microscope image of the newly discovered bacterium flagelium. 2.(Efficiency) Shorter and more effective form of expression rather than long phrases. ie: Family tree, between family members Mendelian autosomal representation of the newly discovered disease. 3.(Emphasis) 4

Figures Used in Reports –Chart, –Diagram, –Flow chart, –Photo, –Radiological image, –Micrograph, –Anatomical drawings, –Family tree, –Map. 5

Features of The Grafics Each table should have a sequence number and title. The title must respond to what, where and when questions. The variables which are shown by the vertical and horizontal axis, also units of these if any, should be stated clearly. Usually the dependent variable is shown in vertical axis and undependent varibel is shown in horizontal axis.

Features of The Grafics Graphic should not be converted into a complex with a number of lines or curves. Graphics are often arranged to show summaries of important data and the highlight points. So, it is incorrect to give many details in this regard.

Frequency Distribution The empirical (experimental) frequency distribution; It is shown in terms of observations of each variable, their classes, or categories of observation frequency. Instead of frequency, by using relative frequency, we can compare the frequency distribution between two or more groups. 8

FrequencyPercent Valid Percent Cumulative Percent ValidSingle 245,65,7 Married 33577,979,885,5 Divorced 204,74,890,2 Widow 419,59,8100,0 Total 42097,7100,0 MissingNo response 3,7 System 71,6 Total 102,3 Total ,0

Types of Graphic You Know?

Displaying The Frequency Distribution Frequency distributions are used for categorical data, or some integer numerical data; It ensures that the data presented visually. Line Graphic (Frequency polygon) Bar or column chart Pie chart Histogram Dot plot Boxplot Scatter diagram 11

Line Graphic (Frequency polygon) It is used in the graphic presentation of continuous data. The horizontal axis (x axis), usually variable is time. Vertical axis (y axis) varies according to the x axis. -Both are indicated by their extent.

Graphs>Legacy Dialogs>Line>Category Axis Let us drag “Duration” variable]>OK

Displaying The Frequency Distribution Bar or column chart: –It is drawn a separate horizontal or vertical column for each category. –The length of the column is proportional corresponding to the category of variable frequency. –The spaces between the columns indicates that the variables are categorical or integer. 16

Let us open the file with SPSS. Let us look at the frequency distribution of “Marital status“ variable and have the column chart. -Analyze> Descriptive Statistics > Frequencies > [ Let us bring "Marital status" variable into "Variable (s)“ area ]> OK Now, let us show the same frequency distributions with column chart: -Graphs> Interactive > Bar [Let us put “Marital status” variable on X axis> OK

Pie chart : Circular pie is divided into slices to represent the frequency of each related variables. Graphs> Interactive > Pie > Simple [ Let us drag “Marital status” variable into the Slice by box. Selecting the “Pies” tab and marking “Percent” check box ]> OK 19

Histogram : This graph is similar to the column chart. However, there is no space between columns. Columns represents the certain range of values, not a value. The graph is used for more in numeric variables to study the shape of the distribution of the data. Let us draw the histogram of "Weight " variable. Graphs> Interactive > Histogram [Let us drag “Weight” variable on X-axis Selecting the “Histogram” tab and marking “Normal curve” check box ]> OK

Dot plot : Is a graphic way which we use frequently. Each observation is represented as a point in horizontal or vertical axis. It can be difficult to interpret this graph in large data sets. (Points will overlap). 23

Boxplot (Stalked box graph): Is also called as elevator graph, box and whiskers chart (box and whisker plot). 25

Scatter diagram: (Scatter plot, dot graphics): Scatter diagram is one of the ways to show with graphs of two separate numerical or ordinal variables. Graphs> Interactive > Scatterplot [Let us drag "Height " variable on X-axis and “Weight” variable on Y axis ]> OK 27

The Shape of the Frequency Distribution Which statistical tests that we apply depends largely on the distribution of our data. In general, our data is unimodal distribution, as there is only one peak point. Sometimes a bimodal (two peak) and uniform (all data are equal) distribution can also be in question. It is important to see how the data is distirbuted between the largest and smallest values in unimodal data. 29

Features that we want to look at in our data are especially as followings: –Symmetric distribution : Evenly distributed around a mean value. In histogram graph, two sides of the bell curve is symmetrical. –Right skewed (Positive skew) : The tail of the bell curve, is to the right in histogram. –Left skewed (Negative skew): The tail of the bell curve, is to the left in histogram. 30

Summary 32