You will be given a data set (on a computer), a hypothesis, and a prediction.

You will be asked the following questions (word for word):

1. Which statistical test should you use? (2

points) 2. What is the p-value? (5 points) 3. Do the data support the prediction (yes or

no)? (3 points)

Practical

Everyone will use Excel on a university computer.All p-value cutoffs for statistical significance will be

0.05. Statistical tables will be provided in the test

spreadsheet. This will be closed book and “closed computer.” No

other windows on your computer may be open. No external devices such as jump drives are allowed.

The formula for the t-test will be given, but it will appear regardless of which test you should use.

You will have one half hour.July 18-19

Know Excel functions for t-test and correlations

(The introduction to Excel lab) and other past exercises

Summary of Statistical Tests (in the manual)Ask questionsBe sure you know how to figure d.f.Know how to use the statistical charts

How to prepare?

If you’re off on d.f., you will probably miss the whole problem.

t-test: n1 + n2 – 2Correlation: n1– 2

D.F.

data data

1 4.00 0.02

2 0.00 0.00

3 1.00 0.00

4 3.00 0.01

5 3.00 0.01

t-test: n1 + n2 – 2how many d.f.?

Correlation: n1– 2how many d.f.?  

First, practice!

t-test: You’re trying to see if there is a difference between the averages of two data sets. These data sets will always be in the same units. Each data point will be a single measurement.

Correlation: You’re testing to see if there is an association between two data sets. This is the test for which scatter plots are helpful (but you won’t make any graphs on the test). These data sets will usually be in different units.

Binomial: Gives the probability of getting results involving repetitions of an experiment which can have only two outcomes. Since these are repetitions, each data point is a count, not a measurement (frequency or % is the actual measurement). Also, binomial data are paired, t-test data are not.

  No credit will be given for doing the wrong statistical test correctly or for

getting the right answer by doing the wrong test.

How do you know which test to use?

Deer harvested Deer harvested

heavily hunted lightly hunted heavily hunted lightly hunted

Deer number antler points antler points Feed type

average no of antler

points

average no of antler

points

1 4 5 1 4 5

2 5 6 2 5 6

3 7 6 3 7 6

4 6 2 4 6 2

5 6 5 5 6 5

6 6 4 6 6 4

7 5 4 7 5 4

8 4 3 8 4 3

9 3 2 9 3 2

T-test or Binomial?

Be familiar with the following functions in Excel: AVERAGE, STDEV, VAR, CORREL, SQRT, TTEST, ^2.

CORREL does not give a p value, TTEST does.Know the difference between S^2 and S and what these

mean.Which way is significant; greater than or less than

0.05? In a correlation, a negative significant relationship is a

significant relationship. If you get a negative r value, report it as such. Change a negative r to positive before looking it up in the chart.

If you get a significant p-value, do you support the prediction for your alternative hypothesis or not?

A few more helpful points :