Randomness Math Example 4
Follow the full solution, then compare it with the other examples linked below.
Example 4
hardDesign a procedure to randomly assign 20 students into two groups of 10 for an experiment, using a random number table or calculator. Explain why randomization matters.
Solution
- 1 Number students 01–20; use a random number generator to produce numbers from 01–20
- 2 Assign the first 10 unique numbers generated to Group A; remaining 10 to Group B
- 3 Ignore repeats and numbers outside 01–20
- 4 Why it matters: random assignment distributes all known and unknown confounding variables equally between groups, allowing causal conclusions
Answer
Use numbered random selection. Randomization balances confounders and enables causal inference.
Random assignment is the hallmark of a controlled experiment. Without it, groups may differ in ways that confound results (e.g., one group is smarter or healthier). Randomization makes groups comparable in expectation.
About Randomness
Randomness is the quality of having no predictable pattern at the individual level, yet following precise probability rules over many repetitions — outcomes are uncertain one at a time but statistically regular in the long run.
Learn more about Randomness →More Randomness Examples
Example 1 easy
A coin is flipped 10 times and lands heads every time. A student says 'the next flip must be tails.'
Example 2 mediumA random number generator produces: 3, 7, 1, 9, 2, 8, 5, 4, 6, 10 (each number 1-10 equally likely).
Example 3 easyA student says 'I picked lottery numbers 1,2,3,4,5,6 — these can't win because they're not random.'