Study Types
A school administrator wants to determine if a new homework policy improves student grades. She implements the new policy in one grade and keeps the old policy in another. What type of study is this?
Experiment
A researcher wants to survey a college campus. They get an alphabetical list of all students and select every 50th name to be a part of the sample. What type of sampling is this?
Is a student's hair color considered quantitative or qualitative data?
Qualitative
What is one way that you can distort a circle graph?
Make the slices unproportional to the percentages.
A survey is sent via email, and only 5% of the people respond. What is a potential source of bias in this scenario?
Nonresponse Bias
A marine biologist tracks a pod of dolphins for a month, recording their migration patterns and feeding habits without interfering with them. What type of study is this?
Observation
A principal wants to get a sample of 30 students. He puts all the students' names into a hat, shakes it up, and draws 30 names at random. What type of sampling is this?
Random Sampling
A researcher is collecting data on the height of plants in centimeters. Is this quantitative or qualitative data?
Quantitative
What is one way that you can distort a bar graph?
Uneven spacing or start at a number other than 0
A school administrator wants to know if students like the new lunch options, so he surveys only the students who are eating lunch in the cafeteria. What type of bias is this?
Convenience Bias or Selection Bias
What is the fundamental difference between an experiment and an observational study?
You DON'T change the environment in an observation; you do in an experiment.
A company has employees in three different departments: marketing, sales, and operations. They want to survey a sample of employees and ensure each department is proportionally represented. They randomly select a number of employees from each department. What type of sampling is this?
Stratified Sampling
A teacher wants to find out the most popular sport among students. Formulate a question that would yield qualitative data to address this.
Example: "What is your favorite sport?"
What does starting at a number other than 0 on a bar graph do to the data?
Exaggerate the differences between the values
A television news program asks its viewers to call in and vote on whether they support a new law. The majority of callers vote "yes." What kind of bias is this?
Self-selected bias
A study investigates the effects of fertilizer on plant growth. What is the variable in this scenario?
Plant growth
A researcher is studying households in a large city. She divides the city into 50 different blocks. She then randomly selects 10 of these blocks and surveys every household within those 10 selected blocks. What type of sampling is this?
Cluster
A researcher wants to determine if there is a relationship between the number of hours students study and their test scores. Formulate a question that would yield quantitative data to address this.
Examples: "How many hours on average do you spend on studying per week" and "What was your most recent test score?"
What kind of graph should you use when comparing values to their portion of the total to avoid misrepresentation?
Circle Graph
A company wants to assess its customer satisfaction. The company sends out a survey to customers who have made a purchase in the last month but only includes a return envelope for a prepaid response. However, the survey questions are phrased in a way that seems to favor the company. What two types of bias are most likely to be present in this survey?
Non-response Bias and Leading Questions Bias
Why is it crucial for an experiment to have a control group?
The control group serves as a baseline for comparison. It helps ensure that any changes observed in the treatment group are a result of the treatment itself and not from other external factors.
A journalist wants to get public opinion on a new local law. He goes to a busy shopping mall and interviews the first 200 people he sees. What type of biased sampling is this, and why is it a problem?
This is convenience sampling. It is problematic because it's not a random sample and will likely be biased, as it only represents people who happen to be at that mall at that specific time.
A biologist is collecting data on animals in a forest. Give one example of a statistical question that would require quantitative data and one that would require qualitative data.
Example: Quantitative: "What is the average weight of the deer in the forest?" Qualitative: "Which species of bird is most common in the forest?"
Which part of the bar graph is most likely to be manipulated in order to distort data?
Y-axis
A researcher wants to study the effects of exercise on sleep. A potential lurking variable is a factor that is not part of the study but may influence the results. Give one example of a lurking variable in this scenario.
Examples include diet, stress level, age, or underlying health conditions.