Peer Review

Dotplot Summaries

Material Detail page

Reviewed:: Feb 22, 2007 by Statistics

Bookmark

Ratings

Overall Rating:

Content Quality:

Effectiveness:

Ease of Use:

Overview:: This applet generates dotplots for different data sets and allows users to guess the location of various measures of center and spread. Clicking "Resample produces a dotplot of random data generated by the applet. A dotplot of user-input data can be generated by clicking Edit Data and typing or copy and pasting the data in the textbox. To guess the mean, median, standard deviation, and interquartile range (IQR) users check the Guess Mean/Median, Guess Deviation, or Guess IQR box and slide the relevant marker along the horizontal axis. When Guess Deviation is selected, users can also select Show Percentages to display the percentage of data points within the users current guess for standard deviation. Clicking Show Actual displays the actual position of the selected measure on the dotplot. Clicking on an individual data point shows its value. Users can edit the data under Edit Data or by clicking and dragging the data points on the graph.
Type of Material:: Java applet
Recommended Uses:: This applet could be used as part of an in-class demonstration or teacher-created activity to introduce or to generate dotplots.
Technical Requirements:: Java enabled Internet browser.
Identify Major Learning Goals:: This applet can help students visualize the positions of the measures of center and spread in a distribution, understand how they relate to each other in a dotplot, and see the dotplot as a simple visual display of the distribution of a measurement variable.
Target Student Population:: This applet is appropriate for introductory statistics students or any statistics course that covers dotplots.
Prerequisite Knowledge or Skills:: The ability to construct dotplots and understanding of mean, median, spread, and interquartile range (IQR) are needed to best use this applet.

Content Quality

Rating:
Strengths:: The dotplots give an accurate picture of the dataset, and the visuals of mean, median, standard deviation, and IQR superimposed on the dotplot are good. The ability to guess the mean, median, standard deviation, and IQR by actively moving their markers on the plot helps users visualize the position of these measures on a dotplot. The basic strength of these activities is that the student can make a guess and then see how close their guess matches the actual values. The ability to import data or to use the applet to generate random datasets is nice.
Concerns:: When users input data through the Edit Data function, the dotplot displays the correct graph. However, if the values are not listed in order, then the individual data points are reported incorrectly when users click on the data points. Clicking Edit Data again reorders the data and corrects this problem. When the dataset used to generate a dotplot has a large range (i.e. greater than 70), the dotplot produced is small and hard to see. The larger the range, the less presentable the dotplot. The function of the Load Data button is unclear. It appears that users could load data from files on the website, but users will not know the titles of the data files to load. The Resample button generates new data and does not resample from the same dataset, making the term Resample is misleading. Sometimes this data is not easy to work with, and it is unclear where this data comes from. There are no instructions on how to use the applet on the web page itself.

Potential Effectiveness as a Teaching Tool

Rating:
Strengths:: Students can make connections between measures of center and spread and the shape of a distribution by guessing the values from the dotplot. Having the ability to quickly input your own data and generate dotplots in class can be an effective way to introduce the dotplot. The dotplot can also be copied and pasted into a Word document by taking a screenshot of the applet.
Concerns:: The errors mentioned above prohibit this applet from being as effective as it could be.

Ease of Use for Both Students and Faculty

Rating:
Strengths:: This applet is fairly intuitive and easy to use. Because it is focused just on generating the dotplot, the user can experiment with the applet to generate several dotplots.
Concerns:: Without any instructions on the webpage the user can only experiment with the features, and students might not know all of the features and capabilities.

Other Issues and Comments:: This applet is useful for introducing and generating dotplots, however, the lack of instructions on the website requires extra work from instructors to implement the applet effectively.
Creative Commons: