Sampling Distributions Flashcards
Standard Error
Standard error of the mean is equivalent to the SD of a distro of sample means
Sample size rule
as sample size increases, the standard error of the mean is going to decrease
Sampling Distribution (mean)
The distro of all sample means that could be obtained in a particular size from same population.
Sampling without replacement
When you sample some people from a population, you do not “put them back” before sampling again: each subsequent sample comes from a smaller and smaller pool/population.
Sampling With replacement
Each item sampled is “put back” before the next selection, retaining the probability for each item’s selection in subsequent samplings.
Sample Design
A “plan” for how items/indiv will be selected from a pop of interest;
Sample design purpose questions
Does the order of selecting participants matter?
Do we replace each selection before the next, “draw”?
Central Limit Theorem
Distribution of means in random sample distro tends toward a normal, even if population is non-normal distro.
Standard Error (SE) or standard error of the mean
The standard deviation of a sampling distribution
Standard Error Calculation
sqrt of σ^2M=Σ(M- μM)^2/N^n
Or, “The square root of the Variance of sampling distro=The sum of: each sample mean minus the population mean squared/by the number of samples”
Secondary Sampling distribution variance formula
σ^2M=σ^2/n
Or variance of sampling distro=population variance/sample size
Secondary Sampling SD formula
σM=sqrt σ^2/n=σ/sqrt n
Sampling error
The differences across sample means when compared to population means; of which standard error of the mean is a numeric measure.
Law(s) of large numbers
As the population SD decreases, so too does the SE
As the Sample Size increases, the SE decreases.
