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 user's 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.
Content Quality 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.
Content Quality 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.
Ease of Use 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.
Ease of Use 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.
Potential Effectiveness Concerns:
The errors mentioned above prohibit this applet from being as effective as it could be.
Potential Effectiveness 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.
Potential Effectiveness Rating:
Source Code Available:
Source Code Available
Intended User Role:
Free for All