Binom and Poisson
Which sampling technique represents "all from some"
Cluster sampling
A researcher wants to study the effect of a new fertilizer on plant growth. She randomly assigns half of the plants to receive the new fertilizer and the other half to receive no fertilizer. After six weeks, she records the height of each plant.
What is the response variable in this experiment?
The height of the plants
How do you determine if a data point is an outlier of a data set?
A data point is an outlier if it is unusually far from the rest of the data. One common rule is that any value below Q1−1.5×IQR or above Q3+1.5×IQR is considered an outlier.
Classify the following variable as nominal, ordinal, interval, or ratio: The number of hours students study per week.
ratio
What information about the population is necessary before conducting stratified sampling?
You need to know the size or proportion of the population in each stratum.
A nutritionist wants to test whether the color of a plate affects how much food people eat. She serves identical meals on red plates for one group and blue plates for another group.
What is the treatment in this experiment?
Plate color
What is the difference between a box plot and a modified box plot?
A modified box plot indicates outliers.
What is statistics?
The science of extracting information from data.
Why does a convenience sample usually fail to give an unbiased sample?
It tends to sample only the part of the population that is most easily reached.
A researcher surveys 500 people about their exercise habits and their reported stress levels. She then looks for a relationship between how much people exercise and how stressed they feel.
What type of study is this?
Non-experiment (Observational study)
Draw or describe the five-number summary for the dataset: 3, 5, 7, 8, 12, 15, 18. Identify any potential outliers.
min= 3
Q1 = 5
Q2 = 8
Q3 = 15
max = 18
No outliers
Which measures of spread are resistant?
IQR
A teacher wants to survey students in the cafeteria. She makes a list of all 200 students who enter and then selects every 10th student on the list, starting with the 4th student.
What type of sampling method is being used?
Systematic sampling
Why is random assignment necessary in an experiment if researchers want to claim that the treatment caused a change in the response variable?
Random assignment helps ensure that the treatment and control groups are similar in all respects except for the treatment, which reduces confounding variables and allows researchers to infer causality.
Final Jeopardy: A company tracks the following information about its employees:
Employee ID number
Job satisfaction rating on a scale of 1–10
Department (Sales, Marketing, HR, IT)
Annual salary in dollars
Date of hire
Classify each variable as nominal, ordinal, interval, or ratio.
1. Nominal
2. Ordinal
3. Nominal
4. Ratio
5. Interval
Explain the difference between descriptive and inferential statistics.
Descriptive statistics deal with data that we have; inferential statistics deal with data that we don't have.