1. 9a. Charts CSCI N207 Data Analysis Using Spreadsheet Department of Computer and Information Science, IUPUI Lingma Acheson linglu@iupui.edu

2. Purpose of Charts Provide a pictorial representation of your data Help understand data better E.g. N207 Spring Grades AB 1StudentsGrades 2SaraA 3JamesB 4WangD 5OllieA 6ArthurC 7ZoeB 8…

3. Purpose of Charts E.g. Percentage of movie rentals:

4. Purpose of Charts Caution! Charts can be misleading, unfair or exaggerating! E.g. distortion.xlsx

5. Common Chart Elements All charts have some elements in common, including: –Data Range –X & Y Axes –Upper & Lower Bounds –Labels –Graph Type

6. Data Range Generally, you will create a spreadsheet that holds or generates data, then use the graph to illustrate the data. You will select the data you want from a spreadsheet, e.g. B2:B25 AB 1StudentsGrades 2SaraA 3JamesB 4WangD 5OllieA 6ArthurC 7ZoeB 8…

7. X and Y Axes The X axis is the horizontal border of the chart. The Y axis is the vertical border. If the graph looks completely wrong, might need to change the X - Y orientation. Normally you need labels to describe each axis.

8. Upper and Lower Bounds Need to specify the upper and lower limits of the axes. The program will usually try to guess what you want, but you may still need to modify it. You need to be careful changing the lower bound of a graph as it can drastically distort your data. Your upper bound should be no larger than it needs to be.

9. Labels There will usually be an option for setting or changing the labels on a graph. You should use this judiciously. Only use labels if they give necessary information, but remove them if they do not add value. The most important part of the graph is the pictorial representation of the data. Unneeded labels decrease the size of the picture.

10. Types of Data Analysis Univariate analysis –describe and explain the characteristics of a single variable(one data field) –E.g. What is the average grade? How many are above 90? Multivariate analysis –describe and explain the characteristics of multiple variables (e.g., two data fields) –Purpose: find correlation between multiple variables –E.g. What’s the correlation between grade performance and job situation? –Caution: When sorting, sort with expansion so that the relationship between two data items in each row is maintained.

11. Chart Types Need to determine what type of graph best describes your analysis The chart type should be chosen carefully and is dependent on the data to be displayed.

12. Excel Chart Types Chart TypeDescriptionUse to… Column/Bar Charts a series of values across a set of categories using vertical columns or horizontal bars. Univariate analysis. Illustrate a single data set or compare values of multiple data sets across same set of categories. Line Charts a series of values across a set of categories as points connected by a line. Univariate analysis. Illustrate one ore more trends over time, e,g. stock trends. Pie/Doughnut Charts a series of values as a percentage of the whole. Univariate analysis. Illustrate the contribution of each value in the data set to a total. Number of values in the data set should be minimal. Scatter/Bubble Charts x,y coordinate pairs. Multivariate analysis. Illustrate the dependence of one set of values (Y) on another (X).