AP Statistics Unit 1: Data Analysis and Collection
Review AP Statistics Unit 1 through quantitative graphs, summary statistics, sampling methods, bias, study design, and experimental conclusions.
- Syllabus
- Effective Fall 2025
- Course
- AP Statistics
Review AP Statistics Unit 1 through quantitative graphs, summary statistics, sampling methods, bias, study design, and experimental conclusions.
A trainer has two weight lifting classes, Class I and Class II. Each class has 9 amateur adult males and 1 professional adult male. Their body weights and number of bench press reps with 225 pounds are shown in the following dotplots. The professionals are designated as A and B.


Identify the type of study.
An observational study.
Identify and classify the quantitative variables.
Body weight and number of bench-press repetitions with 225 pounds; both are numerical.
Determine the population for a valid investigative question.
All amateur males signing up for the trainer’s classes.
An environmental research agency conducted a study of a certain state's roadsides to estimate the mean number
of discarded cans and bottles per mile of public road. The state's public roads were grouped into three types:
Major highways: major paved roads designed for high traffic volume
Minor highways: smaller paved roads designed for low traffic volume
Unpaved roads: gravel and dirt roads
There are about 100,000 miles of public roads in the state. The environmental research agency defined a
sampling unit to be a one-mile segment of public road. Using a database supplied by the state's department of
transportation, the agency randomly selected 30 one-mile road segments for each of the three types of roads.
Researchers from the agency searched the roadsides along each of the selected one-mile road segments and
recorded the number of discarded cans and bottles. Results are shown in the table below.

Question 3
Intent of Question
The primary goals of this question are to assess a student's ability to: (1) identify the variable and
parameter of interest in a study, (2) recognize the type of sampling used in the study, and (3) recognize
which of two methods gives an unbiased estimate for the population mean.
Solution
What is the variable of interest in the study?
What is the parameter of interest?
Part (a):
The variable of interest is the number of bottles/cans per one-mile segment.
The parameter of interest is the mean number of bottles/cans per one-mile segment of all roads in the
state.
Were the data in the study obtained by a simple random sample, a stratified random sample, or a cluster
sample? Explain.
Part (b):
This survey was conducted as a stratified random sample with three strata corresponding to the three
road types: major highways, minor highways, and unpaved roads. Separate random samples of 30 one-
mile segments were taken within each of the three strata.
A horticulturist plans a study on the use of compost tea for plant disease management. She obtains 18 identical beds, each containing a random selection of five minipink rose plants. Some bed or beds will not receive compost tea. For those beds receiving compost tea, she plans to use two different composting times (2 and 5 days), two different compost preparations (aerobic and anaerobic), and two different spraying techniques (with and without adjuvants). Midway into the growing season she will check all plants for rose powdery mildew disease.
Identify the experimental units.
The experimental units are the 18 beds.
Identify the treatments.
There are nine treatments: no compost tea, plus the eight combinations of 2-day or 5-day composting, aerobic or anaerobic preparation, and spraying with or without adjuvant.
Explain why the horticulturist included a group that does not receive compost tea.
The control group determines whether using no compost tea is better or worse than using any of the eight compost-tea applications.
Explain the advantage of using only minipink roses in this study.
Using only minipink roses reduces variability and increases the likelihood of detecting differences among the treatments.
Explain a disadvantage of using only minipink roses in this study.
It limits the scope of the experiment and makes generalization to other rose species difficult.
Using the proportion of plants in each bed that are infected, identify an appropriate graphical representation.
Use a bar chart; each bar height represents the proportion of infected plants in a bed.
Explain why a histogram would not be appropriate.
A histogram displays the distribution of a quantitative variable, whereas the beds are categorical.
Determine a valid investigative question about infection proportions in beds using aerobic and anaerobic preparations.
Is there convincing statistical evidence that the proportion of minipink rose plants infected with rose powdery mildew differs between beds using aerobic preparations and beds using anaerobic preparations?
Tropical storms in the Pacific Ocean with sustained winds that exceed 74 miles per hour are called typhoons. Graph A below displays the number of recorded typhoons in two regions of the Pacific Ocean-the Eastern Pacific and the Western Pacific-for the years from 1997 to 2010.

GRAPH A
Compare the distributions of yearly frequencies of typhoons for the two regions of the Pacific Ocean for the years from 1997 to 2010.
Part (a):
The Western Pacific Ocean had more typhoons than the Eastern Pacific Ocean in all but one of these years. The average seems to have been about 31 typhoons per year in the Western Pacific Ocean, which is higher than the average of about 19 typhoons per year in the Eastern Pacific Ocean. The Western Pacific Ocean also saw more variability (in number of typhoons per year) than the Eastern Pacific Ocean; for example, the range of the frequencies for the Western Pacific is about 21 typhoons and only 10 typhoons for the Eastern Pacific.
For each region, describe how the yearly frequencies changed over the time period from 1997 to 2010.
A moving average for data collected at regular time increments is the average of data values for two or more consecutive increments. The 4 -year moving averages for the typhoon data are provided in the table below. For example, the Eastern Pacific 4-year moving average for 2000 is the average of 22, 16, 15, and 21, which is equal to 18.50.

Part (b):
The Western Pacific Ocean had a decreasing trend in number of typhoons per year over this time period, especially from about 2001 through 2010. In contrast, the Eastern Pacific Ocean was fairly consistent in the number of typhoons per year over this time period, with a slight increasing trend in the later years from 2005 through 2010.
Show how to calculate the 4-year moving average for the year 2010 in the Western Pacific. Write your value in the appropriate place in the table.
Part (c):
The four-year moving average for the year 2010 in the Western Pacific Ocean is
28+27+28+18/4=25.25.
The value is written in the table as follows.
⋮
⋮
⋮
⋮
⋮
2008
20
20.25
27
28.75
2009
23
21.75
28
29.25
2010
18
20.00
18
25.25
Graph B below shows both yearly frequencies (connected by dashed lines) and the respective 4-year moving averages (connected by solid lines). Use your answer in part (c) to complete the graph.

GRAPH B

Completed Graph B showing the 2010 Western Pacific 4-year moving average at 25.25.
Consider graph B.
What information is more apparent from the plots of the 4-year moving averages than from the plots of the yearly frequencies of typhoons?
The overall trends across this time period were more apparent with the moving averages than with the original frequencies. The moving averages reduce variability, making more apparent the overall decreasing trend in number of typhoons in the Western Pacific Ocean and the slight increasing trend in the number of typhoons in the Eastern Pacific Ocean.
What information is less apparent from the plots of the 4-year moving averages than from the plots of the yearly frequencies of typhoons?
The year-to-year variability in number of typhoons is less apparent with the moving averages than with the original frequencies.