Useful Tips on StatCrunch for Math 201:

Summary Statistics

This is where you can find the mean, median, mode, Q1, Q2, and the Standard Error. 

  1. Input the data
  2. Go to Stat -> Summary Stats -> Columns
  3. Click on the variable that you want the summary stats.  (You should always name the variable)
  4. Click on Calculate

The summary stats should appear.

To save your results, click on Options-> Export/Save/Print

This will also put the results at the bottom of your spread sheet.  You can then copy and paste it into a Word document.  Make sure that when you copy your results, you also highlight the title along with the graphics.  Otherwise, it will not paste correctly.

Confidence Intervals

To construct a confidence interval for a mean.

  1. Enter the data
  2. Go to Stat -> T-Statistics -> One Sample
  3. Click on the variable that you want for the confidence interval.
  4. Click on Next
  5. Click on the Confidence Interval Radio Button and enter your confidence level if it is not 95%.
  6. Click on Calculate

The Confidence interval should appear.  You can save and export as in the Summary Statistics

Hypothesis Testing

To construct a Hypothesis Test for a mean.

  1. Enter the data
  2. Go to Stat -> T-Statistics -> One Sample
  3. Click on the variable that you want for the hypothesis test.
  4. Click on Next
  5. Type in the right hand side of the hypotheses.  For example if H0:  m = 10 then type in 10.
  6. Click on the alternative hypothesis arrow and select according to whether it is a left, right or two tailed test.
  7. Click on Calculate

The results of the hypothesis test should appear.  You can save and export as in the Summary Statistics

 

Regression Analysis

To find the equation of the least squares regression line, the correlation, a confidence interval for y given x, the P-Value for the slope and correlation, and to plot the scatter plot and regression line.

  1. Enter the data in two columns
  2. Go to Stat -> Regression -> Simple Linear
  3. Select your X-Variable (the independent variable or the predictor)
  4. Select your Y-Variable (the dependent variable or the variable you want to make a prediction of.
  5. Click Next
  6. Click on Predict Y for X = and fill in the value of x that you want a confidence interval for.
  7. Click Next
  8. Click on Plot the fitted line
  9. Click Calculate

The readout should appear.

The fourth line shows the equation of the regression line.  Note that is will not have x and y shown, but rather the names that you have given for x and y.  For example:

HoursWorked = 18.3345123 - 0.2513213UnitsTaken

The sixth and seventh lines are the correlation and the coefficient of determination.

The P-Value for both the slope and the correlation are given in the first table in the cell with row Slope and column P-Value.

In the third table you will see a confidence interval (CI) and a prediction interval (PI).  The confidence interval is the confidence interval for the average of y values that have the specified value of x.  The prediction interval is the confidence interval for a specific value if y given a value of x.

If you click on the next button, you will find the scatter plot and regression line.

The Difference Between With Data and With Summary

There are two ways of making charts.  One With Data and the other With Summary.  For  example if you want to make a pie chart of data that has five greens, ten reds and 19 blues, you can create two columns.  Label the first column "color" and the second column "count".  The rows of the first column should contain the words:  green, red, and blue.  The second column should contain the numbers 5, 10, and 19.  Then when you go to Graphics -> Pie Chart -> With Summary.  For Categories In select color and for Counts In select count.  The rest should be self explanatory.

If instead the data is given by listing green five time, red ten times blue 19 times all in one column, then  go to

Graphics -> Pie Chart -> With Data

And the rest should be self explanatory.