Our method of confidence intervals provides an interval estimate of the population parameter at a certain success rate called the confidence level. When we do not know much about the population, we ca...Our method of confidence intervals provides an interval estimate of the population parameter at a certain success rate called the confidence level. When we do not know much about the population, we can utilize random sampling to build confidence intervals to learn about populations from scratch. At other times, we have claims about a certain population that we hope to test. This quest falls within the realm of inferential statistics and is the subject of this chapter.
The Type 2 Error rate and the magnitude of the error for a point estimate are controlled by the sample size. Real differences from the null value, even large ones, may be difficult to detect with smal...The Type 2 Error rate and the magnitude of the error for a point estimate are controlled by the sample size. Real differences from the null value, even large ones, may be difficult to detect with small samples. If we take a very large sample, we might nd a statistically significant difference but the magnitude might be so small that it is of no practical value. In this section we describe techniques for selecting an appropriate sample size based on these considerations.
