It is important to note that an action will be made (i.e. increase or decrease visits) if the average fill shifts away from in either direction. Since we are looking for statistical evidence of an average shift in either direction, the appropriate hypotheses and test procedure are:

- 1.
- Hypotheses: versus
- 2.
- Test Statistic:
- 3.
- P-value: Presuming
*H*_{0}is true, the likelihood of chance variation yielding a*t*-statistic more extreme than -2.01 on*either side*of 0 (since*H*_{1}direction is both high and low) is .11. - 4.
- Conclusion: Since P-value > .05, we do not reject
*H*_{0}. The sample does not provide enough evidence that the mean fill has shifted from 70%.

Summary of the **two-tailed** *t*-test for :

- versus
- Test statistic:
- P-value: Total area
*greater than*|*t*|*and less than*-|*t*| under*t*-curve with*n*-1 degrees of freedom If*t*is far enough from 0*on either side*(the direction of*H*_{1}), the P-value will be small. - Conclusion:
If P-value
.05, we reject
*H*_{0}with statistical significance. If P-value .01, we reject*H*_{0}with high statistical significance. If P-value>.05, we do not reject*H*_{0}.