AP Statistics Exam, Free Response Questions: Any patterns?

The free response questions for the AP Statistics exam are sometimes hard to predict.  What trends do exist?

Here is A graph relating AP Free response question Number vs.  Chapter in the  5^th Edition of The Practice of Statistics.

1:           Exploring Data (single variable, quantitative)
2:           Modeling Distributions of Data  (z-scores, percentiles, normal model)
3:           Describing Relationships
4:           Collecting Data
5:           Probability, the basics
6:           Random Variables, the binomial and geometric distribution.
7:           Sampling Distributions
8:           Inference: Confidence Intervals, 1 variable.
9:           Significance Tests, 1 variable.
10:         Inference for two groups
11:         Inference for categorical data
12:         Inference for regression

Here’s a graph of the relationship. Here are a few trends I observe:

1. Question 1 tends to be exploratory data analysis OR an easier test about inference.
2. Question 2 seems to feature probability OR sampling/ experimental design
3. Question 3 seems to feature probability OR sampling/ experimental design
4. Question 4 seems to feature an inference procedure often, but not always
5. Question 5 seems to feature an inference procedure often, but not always.
6. Question 6 always is a mixed bag, bot often involves some reasoning regarding inference.

Other observations:

• “Probability, served three ways:”  Probability questions are often, but not always, three-parters that take a single scenario and then “serve up” questions involving three different techniques in probability.
• Two sample t  vs Matched Pairs t questions are common.
• Inference for regression, when addressed, is done pretty lightly, and often in question 6.  There are often many other parts to question 6 that are not about inference for regression.