Essay On Graphs Describing Data Discussion Forum

Descriptive Statistics

Introduction
Graphs are a potent medium to visually compact large amount of data and present it to the viewer for ease of comprehension. However, the viewer must be aware of faulty graphs that may prove to create misperception in the mind of the viewer.

Faulty Graphs

Figure 1: Sales Data (Trulia, n.d.).
The sales data from Trulia relates to the Sacramento real estate market. On the face of it, the graph shows that there was a major dip in sales in 2008. The naked eye would see the peak in sales corresponding to the year 2005-6, and the trough in 2008. It appears that the sales in 2008 were around 40-50% of the sales in 2005-6, as the height of the line graph corresponding to the year 2008 is at approximately half the height of the line at the year 2005-6 (Trulia, n.d.).
A closer inspection of the graph, however, reveals the flaw that creates this misperception. The y-axis of the graph does not begin at zero. Rather, it begins at 1000. Had the y-axis begun at zero, the graph would have appeared in correct proportion and context. Further, the y-axis does not show a uniform scale. The data at the higher end of the scale is compressed, akin to a logarithmic scale. Therefore, it becomes merely the judgment of the viewer to draw his conclusions about the sales figures.

Conclusion

Most graphs where the presenter wishes to magnify the good or bad news would tend to adopt the trick of misrepresenting the origin of the graph. If the y-axis does not begin at zero, a minor rise could be depicted as a major accomplishment, and conversely, a minor dip could be shown as a major loss. Therefore, it is important to ascertain the scale and the coordinates at the intersection of the x and y-axes in order to get the correct perception of the graph.

Reference

Trulia. (n.d.). Sacramento market trends. Retrieved April 15, 2015, from http://www.trulia.com/real_estate/Sacramento-California/market-trends/