This page helps readers know which statistcal tests are appropriate for the different types of data. Two charts display the information. A discussion of study design and sample size, as well as exercise questions with solutions are also provided.
This applet introduces the concept of confidence intervals. Select an alpha level, sample size, and the number of experiments, and click "Play." For each sample, the applet will show the data points as blue dots and the confidence interval as a red, vertical line. The true population mean is shown as a horizontal purple line, and green ovals indicate which intervals do not contain the true mean.
This applet demonstrates the Normal approximation to the Poisson Distribution. Users can set the rate, lambda (‘é), and the number of trials, n, and observe how the shape of the distribution changes. The Poisson distribution is shown in blue, and the Normal distribution is shown in red.
This applet demonstrates the Binomial distribution by simulating Galton's Board, dropping balls through a triangular array of nails. When a ball hits a nail, it has a 50 percent chance of falling to the left or the right. Because Galton's Board consists of a series of experiments, the piles under the board are the sum of n random variables, where n is the number of rows of nails on the board.
This applet demonstrates the Central Limit Theorem. First, select a distribution (Normal, Uniform, Skewed, Custom) and add or delete data points by clicking on the graph. Then, sample from the parent population and the distribution of the sample mean is shown. Users can also choose to see the distribution of the median, standard deviation, variance, and range.
This page contains links to 5 review sheets with formulas, properties, definitions and rules for basic descriptive and inferential statistics and probability concepts. The review pages are in pdf format. Key Words: Hypothesis Testing, ANOVA, Descriptive Statistics, Regression, Correlation, Nonparametric Tests, Probability Distributions, Counting, Central Limit Theorem.
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.
This applet shows a scatterplot of height versus foot length. Users can add or delete points and then guess the regression line by clicking "Your Line" and moving the blue regression line. By clicking "Regression Line" users can see the actual regression line. The applet also shows the correlation and R-square for the data as well as the residuals and squared residuals for the guessed regression line and the actual regression line.
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.
