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Statistics Unit 3
Unit 3 Sampling Distribution of sample mean
Question | Answer |
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The sampling distribution of a sample statistic x is | the probability distribution of x across all possible samples taken from the population. |
The sampling distribution of a sample statistic is determined by the following factors: | •frequency distribution of the variable of interest in the entire population •random sampling method to be used •size of the sample to be taken |
In order to make inferences (probabilistic statements) about the value of some population parameter, we need to know | the sampling distribution of the sample statistic used as a point estimator. |
When the sampling distribution is Gaussian normal, the knowledge of two parameters is sufficient: | •expected value • standard deviation |
A finite population is treated as infinite if | n/N<0.05 |
Example: What is the probability that a simple random sample of 30 applicants will provide an estimate of the population mean SAT score that is within 10 of the actual population mean u ? | Step 1: Calculate the z-score at the upper endpoint of interval. S2: Find the area under curve to the left of upper endpoint. S3,4 repeat the same but from the other side S5: Cal area under curve between lower and and upper endpoints of interval |