Section 10.5: The Normal Curve and Sampling
- The frequency distribution illustrated by the following illustration is
known as the normal curve. The mean is and the standard deviation is ,
with the percents of the distribution shown in each measured section (each
one being one standard deviation).
- If a researcher wants to find information about a population he/she
can query all members of the population, or can select a subset of the
population. The selection of a subset of the population is called sampling.
This sampling is designed to tell the researcher something about the
population. The item being researched is called the hypotheses. There
are two types of error due to sampling:
Type I: Rejection of the hypothesis when it is true.
Type II: Acceptance of the hypothesis when it is false.In an a attempt to minimize error in their predictions, statisticians follow very careful procedures:
Step 1. Propose some hypothesis about a population.
Step 2. Gather a sample from the population.
Step 3. Analyze the data.
Step 4. Accept or reject the hypothesis.