One Numerical Variable

  • 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.
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  • This applet allows users to calculate probabilities from a normal distribution. First, set the mean and standard deviation and click "Scale to Fit". Check one of the boxes next to the inequality signs and enter a value for x; the applet will calculate the z-score and cumulative probability (shown in dark blue for top value and pink for the bottom). By clicking both boxes, users can see the probability between two values (in pink) or outside two values (in blue). Click the inequality sign to change the direction of the cumulative probability.
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  • This resource defines and explains the arithmetic mean using an example on employee salaries.
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  • This resource defines and explains the median using an example on employee salaries.
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  • This resource defines and explains percent changes using an example on city murder rates.
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  • This resource defines and explains per capita rates using an example on city murder rates.
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  • ... statistics - whatever their mathematical sophistication and elegance - cannot make bad variables into good ones. Quoted from "Analysis of Nominal Data" by H.T. Reynolds (Sage, 1984) p. 8
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  • The great tragedy of Science - the slaying of a beautiful hypothesis by an ugly fact. A quote of English biologist Thomas H. Huxley (1825 - 1895) from his Presidential address in 1870 to the British Association for the Advancement of Science. Published in "Biogenesis and Abiogenesis," vol. 8, Collected Essays (1894).
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  • I don't see the logic of rejecting data just because they seem incredible. A quote of British Astronomer Sir Fred Hoyle (1915 - 2001) found in "Statistically Speaking - A Dictionary of Quotations" compiled by Carl Gaither and Alma Cavazos-Gaither (IOP publishing, 1996) p. 150.
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  • This JAVA applet assists the user in developing skills to classify a problem as one of the various types of confidence intervals, hypethesis tests and Chi Squared tests. This is not an easy application, but the comprehensive hints provided will improve the users skills in making such classifications.
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