Separate Random Assignment from Random Sampling
Random assignment distributes participants among treatment groups to reduce systematic preexisting differences.
About 25 minutes, plus any extended practice
Open lesson 1Statistics: Study Design and Careful Inference
Evidence quality depends on how participants and conditions are selected. Random sampling supports population generalization, random assignment supports treatment comparisons, and uncertainty summaries do not repair biased recruitment or uncontrolled causal differences.
Before you begin
- Interpret percentages, averages and samples; distinguish observation from assigned treatment.
Choose by skill rather than age alone. Read with an adult when useful, revisit a lesson, or explore another grade.
Follow the lesson sequence
Interpret Variation across Repeated Samples
Repeated samples from one model can give different means.
About 25 minutes, plus any extended practice
Open lesson 2Use Percentage Points in a Reported Interval
A reported estimate with an additive margin produces endpoints by subtracting and adding the margin.
About 25 minutes, plus any extended practice
Open lesson 3Keep an Observational Association Qualified
An observational score difference can reflect preexisting differences between groups as well as an intervention.
About 25 minutes, plus any extended practice
Open lesson 4Review and transfer
After the lessons, try 4 new review cases and a practical task. Each answer has an explanation and a link back to the related lesson.
Open the unit reviewGuest answers are temporary. Keep your own paper or document; this unit does not certify completion or record a school grade.
Topic references
- California CCSS mathematics topic reference: topic reference — Statistics: Study Design and Careful Inference
These references informed the topic selection. They do not certify complete standards alignment.