What you’ll learn
Use samples to estimate population characteristics.
Key idea
Use a sample fraction to project a population count, retaining sampling uncertainty.
Observed sample counts and projected population counts differ; sampling variation prevents a point estimate from becoming exact census truth.
Worked example
Enter the exact value or ordered values in the format requested below.
A random sample of 10 from a 1700-pupil school finds 1 favoring a later start. Enter the numerical point estimate of schoolwide supporters from this sample share, not an exact census count.
- The random sample has 1/10=1/10 favoring a later school start time.
- Scaling this share to 1700 pupils gives point estimate 170; only the sample was observed, so this is not a known exact schoolwide count.
Answer: 170
Quick Check
Interpret the result of 'Use samples to estimate population characteristics' in the data-generating context, including units and population limits.
School population 400; random sample 30 has 3 favoring a later start. Interpret the population projection with its uncertainty.