1.1 What is stats?

What is the difference between a parameter and a statistic?

A parameter is a numerical measurement describing data from a population. A statistic is a numerical measurement describing data from a sample.

In a statistical study what is the difference between an individual and a variable?

An individual is a member of the population of interest. A variable is an aspect of an individual subject or object being measured.

If there are three different samples of the same size from a set population, is it possible to get three different values for the same statistic?

Data from samples may vary from sample to sample, and so corresponding sample statistics may vary from sample to sample.

What is the average miles per gallon (mpg) for all new cars? Using Consumer Reports, a random sample of 35 new cars gave an average of 21.1 mpg. Variable? Is the variable quantitative or qualitative? What is the implied population?

mpg quantitative all new cars

For a set population, does a parameter ever change?

never

Government agencies carefully monitor water quality and its effect on wetlands (Reference: Environmental Protection Agency Wetland Report EPA 832-R-93-005). Of particular concern is the concentration of nitrogen in water draining from fertilized lands. Too much nitrogen can kill fish and wildlife. Twenty-eight samples of water were taken at random from a lake. The nitrogen concentration (milligrams of nitrogen per liter of water) was determined for each sample. Variable? Is the variable quantitative or qualitative? Implied population?

nitrogen concentration quantitative the entire lake

The archaeological site of Tara is more than 4000 years old. Tradition states that Tara was the seat of the high kings of Ireland. Because of it's archaeological importance, Tara has received extensive study (Reference: Tara: An Archaeological Survey by Conor Newman, Royal Irish Academy, Dublin). Suppose an archaeologist wants to estimate the density of ferromagnetic artifacts in the Tara region. For this purpose, a random sample of 55 plots, each of size 100 square meters, is used. The number of ferromagnetic artifacts for each plot is determined. Variable? Is the variable quantitative or qualitative? Implied population?

number of ferromagnetic artifacts per 100 square meters quantitative the entire Tara region