Chapter 1 Study guide

The ethnicity of the individual respondents in a political poll of a randomly selected group of adults is an example of what type of variable?

Qualitative variable

Census

the collection of data from every element in a population; a sample is a subset of a population.

Identify which of these types of sampling is used: random, stratified, systematic, cluster, convenience.To avoid working late, a quality control analyst simply inspects the first 100 items produced in a day.

Convenience

The average number of hours spent completing statistics homework for a randomly selected group of statistics students is an example of what type of variable?

Quantitative variable

sample

a subset of elements drawn from a population.

Describe a double-blind experiment and explain why blinding is used. Define the term"placebo effect" as part of the answer.

A double blind experiment is one in which neither the subjects nor the researchers know who is getting the treatment. Blinding is when the subject does not know whether he or she is receiving a treatment or a placebo. Blinding is used to counteract the placebo effect in which an untreated subject believes he or she is receiving a treatment and reports an improvement in symptoms due to this belief.

Identify which of these types of sampling is used: random, stratified, systematic, cluster, convenience. An education researcher randomly selects 48 middle schools and interviews all the teachers at each school.

Cluster

Determine whether the given value is from a discrete or continuous data set. The temperature of a cup of coffee is 67.3°F.

Continuous

Determine whether the given description corresponds to an observational study or a controlled experiment. A clinic gives a drug to a group of ten patients and a placebo to another group of ten patients to find out if the drug has an effect on the patients' illness.

Controlled experiment

Determine whether the given value is from a discrete or continuous data set. The number of freshmen entering college in a certain year is 621.

Discrete

Determine whether the given description corresponds to an observational study or a controlled experiment. A marketing firm does a survey to find out how many people use a product. Of the one hundred people contacted, fifteen said they use the product.

Observational study

Determine whether the given value is a statistic or a parameter. After taking the first exam, 15 of the students dropped the class.

Parameter

Identify the sample and population. Also, determine whether the sample is likely to be representative of the population. An employee at the local ice cream parlor asks three customers if they like chocolate ice cream.

Sample: the 3 selected customers; population: all customers; not representative

Determine whether the given value is a statistic or a parameter. A sample of 120 employees of a company is selected, and the average age is found to be 37 years.

Statistic

Identify which of these types of sampling is used: random, stratified, systematic, cluster, convenience. 49, 34, and 48 students are selected from the Sophomore, Junior, and Senior classes with 496, 348, and 481 students respectively.

Stratified

Identify which of these types of sampling is used: random, stratified, systematic, cluster, convenience. A sample consists of every 49th student from a group of 496 students.

Systematic

statistic

a numerical measurement describing some characteristic of a sample.

parameter

a numerical measurement describing some characteristic of a population.

population

he complete collection of all elements.