MDM_presenting_graphs


 * Graphical Representation of Data**

Graphical represenation of data is basically the presentation of data in the form of graphs.

Facts and figures such as those in newspapers or magazines do not catch our attention unless they're presented in an interesting way. That's why the media nowadays is trying to present statistics in a more visually appealing manner, which is in the form of graphs. Graphs excel at showing the relationships/comparisons between variables and making trends easily noticeable. They also make the reading more interesting and less time-consuming. However, their disadvantage could be the fact that they lack details and are less accurate.

Graphical representation of data serve the following purposes
 * 1) to show what has happened
 * 2) to show the relationship between quantities
 * 3) to show distribution

There are many forms of representing data graphically. The main ones include

1. Bar graph 2. Line graph 3. Pie graph/chart 4. Histogram 5. Scatterplot

Which graph to use largely depends on the nature of the data and what variables you are trying to compare. It is important to select a suitable graph to represent the data.


 * Bar graph**

Bar graphs are the simplest type of graphical representation of data. They are typically used for immediate comparison of different items and are preferred when each item is separate from the other. Since the height of the bar represents the "quantity" or "frequency" of an item it is easy to see which item has the most/least amount and how much the "quantity" of each item is in relation to one another.



//Figure 1.// Looking at this graph it is easy to see that the 7th grade has the most number of people taking the bus (since its bar is the highest).


 * Line graph**

Line graphs are usually used to represents time-series data. In other words, they're used to show a development or a trend in a certain variable(s) over time. It doesn't need to be time related however, as the x and y axis can be represented by 2 different variables (with there only being one y value for every value of x.)



//Figure 2.// Above shows line graph of population over a period of time. As you can see the line's going up which means the population is increasing steadily over a period of time.


 * Pie graph**

A pie graph is a circle that is divided into sectors, with each sector representing a different item. The quantities are proportional to the whole, w hich means the pieces representing the items are big or small depending on their percentages to the whole. Pie graphs are most frequently used to show percentages of different groups within a certain population, but the data does not always have to involve people. Pie graphs should not be used when there are too many items, since the numerous sections of the circle will look very messy and will not aid in making the data easier to understand.



//Figure 3.// When there are only a few elements a pie graph is suitable since it's easy to see how big the pieces are in relation to each other and which pieces are dominant. The graph above is an example of a pie graph showing different groups within a certain population.

**Histogram**
 A Histogram is used to graphically summarize and display the distribution of a data set. The x axis is divided into ranges of equal size (also called "bins"). The y axis is labelled frequency (number of counts for each bin). Bars are used to show the frequency for each range. Histograms excel at showing the distribution of data; it shows which range is the most common. A lot of information can be obtained by examining the shape and symmetry of the data. Histograms can also be used to detect bias. For example, where distribution is known, histogram not fitting the distribution provides clues about errors in the survey process and also measurement problems.

[[image:http://media.techtarget.com/digitalguide/images/Misc/iw_histogram.gif width="350" height="407"]]
//Figure 4.// A histogram is used to show the frequency of various score ranges of an exam. This graph is skewed to the right which means most kids passed this exam and only a few failed. The most frequent range is from 60%~80%, and this tells us that this school generally has typical kids because most of them scored around average. If the graph was skewed even more to the right, that would indicate that the school is full of smart kids (and vice versa).


 * Scatter plot**

 Scatterplots are graphs that show the relationship between two variables for a set of data using Cartesian coordinates (points). They are used to record measurements of two or more variables, usually for the purpose of finding a correlation between the two variables. Each point usually represents a single "individual" or data point. A line of best fit is drawn through the points to show general trend. The resulting pattern //may// indicate the type and strength of the relationship between the two variables (a correlation does not always mean that the variables have a cause and effect relationship). Scatter plots are useful when dealing with large numbers of data points and should be avoided when the data set is very small.

  //Figure 5.// The line of best fit has a positive slope, which means that there's a positive correlation between the two variables. This indicates that a person with more years of experience generally has a higher income as well.

**Works Cited**
1. Elert, G. (2009). Graphical Representation Of Data. //The Physics Hypertextbook.// Retrieved from []

2. Concept of Graphical representation of Data. (n.d.) //TutorVista.// Retrieved from []

3. The Histogram. (n.d.) //NetMBA Business Knowledge Center.// Retrieved from []

4. Scatterplots. (2009). //Statistics Canada: Canada's national statistical agency.// Retrieved from []

5. Scatter Plot. (n.d.) //NetMBA Business Knowledge Center.// Retrieved from []