In a paired significance test, you first subtract the two values in each pair, then run the test on the single column of differences.

Circle one:   True   False

A chemist weighs the same flask every morning and every evening for 10 days, and wants to know if the scale drifts between morning and evening. Which test fits this data?

• A paired t-test on the daily differences
• An independent two-sample t-test treating mornings and evenings as separate groups
• A one-sample test against the known flask mass
• A test comparing two proportions

A student claims a new titration matches the standard method on average. What is the null hypothesis?

• The two methods have equal true means
• The new method has a higher true mean
• The two methods used equal sample sizes

You test at 95 percent confidence. As a decimal, what is the significance level?

Answer: ______________

A student claims a new titration method gives the same average result as the standard method. What is the correct null hypothesis for testing this claim?

• The two methods have equal population means
• The new method has a higher mean than the standard method
• The two methods have equal sample sizes
• The two methods have equal spreads

A P-value of 0.40 at the 5 percent level proves the null hypothesis is true.

Circle one:   True   False

Lab A measures the purity of 8 batches of salt with a titration, and Lab B measures 8 different batches of the same salt with a sensor. The chemist wants to know if the two methods give different average purity. Which test should be run?

• A paired t-test, because both labs measure purity
• An independent two-sample t-test, because the batches are different and unpaired
• A one-sample test against the certified purity
• A chi-square test of counts

A lab wants to check whether its new balance gives an average reading that matches the certified reference value of 100.0 mg. Only the lab's own repeated readings are available. Which test applies?

• A one-sample t-test comparing the mean of the readings with the known value
• A paired t-test on the differences between pairs
• An independent two-sample t-test against another lab
• An F-test comparing two spreads

Two analysts measure the same standard solution with two different methods. An F-test on the two spreads gives a significant result at the 5 percent level. What does this significant F-test tell the chemist?

• The two methods differ in precision, so the results should not be pooled as if the spreads were equal
• The two means must be different
• One analyst made a mistake and should repeat the work
• The F-test checks whether the means are equal

Your test at 95 percent confidence returns a P-value of 0.03. Which reading is correct?

• The result is significant, but it does not prove the claim beyond doubt
• The claim is proven true with 97 percent certainty
• The test failed because 0.03 sits below 0.05