Calculator Input
Formula Used
Mean of sampling distribution:
μx̄ = μ
Standard error with replacement:
SE = σ / √n
Finite population correction without replacement:
FPC = √((N - n) / (N - 1))
Adjusted standard error:
SE = (σ / √n) × FPC
Variance of sample means:
Var(x̄) = SE2
Target z score:
z = (target sample mean - μx̄) / SE
How to Use This Calculator
- Enter the population mean and population standard deviation.
- Enter population size when finite correction is needed.
- Enter the sample size for each repeated sample.
- Select sampling with or without replacement.
- Add a target sample mean for probability checking.
- Paste raw population values when exact population data is available.
- Press calculate to show the result above the form.
- Use CSV or PDF buttons to export the result.
Example Data Table
| Scenario | Population Mean | Population SD | Sample Size | Method | Expected Mean | Standard Error |
|---|---|---|---|---|---|---|
| Class test scores | 75 | 12 | 36 | With replacement | 75 | 2 |
| Inventory audit | 420 | 55 | 40 | Without replacement | 420 | Adjusted by FPC |
| Survey rating | 8.2 | 1.4 | 64 | With replacement | 8.2 | 0.175 |
Understanding the Mean of a Sampling Distribution
A sampling distribution describes many possible sample means. Each sample has the same size. Each sample comes from one population. The mean of those sample means has a simple center. It equals the population mean when sampling is random.
Why This Mean Matters
This value helps analysts predict average sample behavior. One sample can be high. Another sample can be low. The full sampling distribution shows the pattern behind those changes. Its mean gives the expected sample average before data collection starts.
Core Statistical Idea
The calculator uses the population mean as the sampling distribution mean. When raw population values are entered, the page first computes the population average. It then uses sample size to estimate spread. The spread of sample means is called standard error. Larger samples usually give smaller standard errors.
Finite Population Adjustment
Sampling without replacement can reduce variation. This happens when the sample is a meaningful part of the population. The finite population correction lowers standard error in that case. The adjustment is useful for audits, classes, inventories, and surveys with limited records.
Target Mean Checks
A target sample mean adds practical context. The calculator converts that target into a z score. It also estimates the probability of getting a sample mean at or below the target. This probability uses a normal approximation. It works best for large samples or nearly normal populations.
Confidence Range
The confidence range shows a central band around the expected mean. It is not a promise for every sample. It is a guide for likely sample mean movement under the selected confidence level. Wider confidence levels create wider ranges.
Using Results Wisely
Use the result as a planning tool. Check the population standard deviation carefully. Use raw population values when available. Choose without replacement only when sampled units cannot return. Review the formulas before sharing outputs. Export the result when documentation is needed.
Common Applications
Teachers use this concept for probability lessons. Researchers use it when planning surveys. Quality teams use it for process checks. Finance teams use it for repeated estimates. The same idea supports many reports. Clear inputs make the output easier to defend. It also improves review speed for busy teams.
FAQs
What is the mean of a sampling distribution?
It is the average of all possible sample means for a fixed sample size. For random sampling, it equals the population mean.
Does sample size change the mean?
No. Sample size changes the spread, not the expected center. The sampling distribution mean remains equal to the population mean.
What is standard error?
Standard error is the standard deviation of sample means. It shows how much sample means usually vary around the expected mean.
When should I use finite population correction?
Use it when sampling without replacement from a known finite population, especially when the sample is a large share of the population.
Can I enter raw population values?
Yes. Paste values separated by commas, spaces, or new lines. The calculator will compute the population mean and deviation from them.
What does the target probability show?
It estimates the chance that a random sample mean is less than or equal to your target sample mean.
Is the probability always exact?
No. It uses a normal approximation. The estimate is usually better for larger samples or populations that are close to normal.
Why export the result?
Exports help save calculations for reports, lessons, audit files, or review notes. CSV suits spreadsheets. PDF suits sharing.