Using Winstats to graph, describe, and analyze data Download Winstats at http://math.exeter.edu/rparris/winstats.html. Save onto your computer. Then unzip the file. The author updates the Winstats program routinely to make improvement and fix bugs. So it is worth checking routinely. Single Variable Data Entering Data

Enter data into an Excel Worksheet, then highlight, and copy the data In Winstats, select 1-Var Data under Window. (or Click F1) Under File, click Paste from Clipboard. (of Ctrl+V) If you want to change the number of decimal places show, under Edit, click Format

and change decimal place. Descriptive Statistics

Under Stats, click Overall. This will give you sample size, the 5-number summary, the mean, the interquartile range, the standard deviation calculations for population (n) and sample (n-1), as well as other measures. Graphs

Boxplots (with outliers represented as dots outside beyond whiskers) o Under Stats, click Boxplot and Boxplot

Histograms o Under Stats, click Histogram and then Number of Groups o A little window for number of groups (or classes) to be used in the histogram

should appear. You can enter the number of classes you wish to use, OR use the slider to examine what happens to the histogram as you increase or decrease the number of classes. The histogram will appear and change accordingly as you use the slider. (Recall: Generally, we want between 5 and 20 classes depending on the sample size. Dont even approach the upper limits given by the program.)

Stemplots o Under Stats, click Stemplot and then Stemplot

Normal Distributions Under Window > Probability, click Normal. A window containing a picture of a

standard normal distribution curve will appear. You can confirm that it is standard normal because the heading is titled Gauss(0.0000, 1.0000, x). Gaussian is another way of describing normal data, the first number in the parentheses refers to the mean, the second number refers to the standard deviation. A standard normal distribution has a mean of 0 and a standard deviation of 1.

Finding an area under the standard normal curve or the probability of being in a particular region. Under Calc, click Probabilities A calculation window appears. Enter the low or left z value for your region (if you are calculating a left tail, entering a big negative will suffice) and enter the high or right z value for your region (if you are calculating a left tail, entering a big positive will suffice). Click the probability button. Next to this button, your desired area (or probability) will appear. Notice that the program will also shade the region for which you calculate the area.

Finding a z-value based on a particular right tail area. If you know the area you need in a tail, you may find the corresponding z-value. Enter that area in next to significance and click the critical x button. The z-value corresponding to a right tail of the entered area will appear to the left of the button. If you need the z-value for the left-tail, make the value negative.

Finding values for any other normal distribution. Change to an alternate normal distribution by clicking on Parameters under Edit. Enter the mean and standard deviation for the desired normal distribution and click OK. The graph will change appropriately. Now you may use the calculation window to find areas under the curve of critical x values related to this distribution.

Students t Distributions

Under Window > Probability, click Student t. A window containing a picture of a t-distribution curve will appear. You must set the curve to reflect the distribution you currently are investigating. Click on Parameters under Edit. Enter the degree of freedom and click OK. The curve will now reflect your choice. The degree of freedom entered will appear as the first number in the parentheses on the heading of the window containing the curve.

Finding the area of a right tail. Under Calc, click Probabilities A calculation window appears. Enter the t-value that bounds the tail under consideration in the box to the right of x-value and click the tail probability button. Next to this button, your desired area (or probability) will appear. Notice that the program will also shade the region for which you calculate the area. (Recall: The curve is symmetrical about the mean. So if you need a left tail area, enter in the associated positive t-value.)

Finding a t-value based on a particular right tail area. If you know the area you need in a tail, you may find the corresponding t-value. Enter that area in next to significance and click the critical x button. The t-value corresponding to a right tail of the entered area will appear to the left of the button. If you need the t-value for the left-tail, make the value negative.

Two Variables Entering Data

Enter data into an Excel Worksheet (one variable per column), then highlight, and copy the data

In Winstats, select Multi-Var Data under Window. (or Click F2) Under File, click Paste from Clipboard. (of Ctrl+V) If you want to change the number of decimal places show, under Edit, click Format

and change decimal place. Also click on column headings and enter variable name. Graphing Data

Under Plot,, click 2D plot 1 A window titled Scatter plot appears. Select the column (1 or 2) that contains the

variable to be on the horizontal axis from the pull down menu hori axis. Select the column (1 or 2) that contains the variable to be on the vertical axis from the options under vert axis. Click OK.

A window with a scatterplot of your data appears. Notice that only the minimum and maximum values are listed for the scale of the plot. For a better scale, click Grid under the View pull down menu.

Single Variable DataEntering DataDescriptive StatisticsGraphsNormal DistributionsStudents t DistributionsTwo VariablesEntering DataGraphing Data