Elementary Statistics Ron Larson and Betsy Farber Chapter 1 Section 1 Elementary Statistics Ron Larson and Betsy Farber

Data: consists of information coming from observations, counts, measurements, or responses.

Statistics: Is the science of collecting, organizing, analyzing, and interpreting data in order to make decisions.

A population is the collection of all outcomes, responses, measurements or counts that are of interest.

A sample is a subset, or part, of a population.

A parameter is a numerical description of a population characteristic. A statistic is a numerical description of a sample characteristic.

Descriptive statistics is the branch of statistics that involves the organization, summarization, and display of data. Inferential statistics is the branch of statistics that involves using a sample to draw conclusions about a population. A basic tool in the study of inferential statistics is probability.

1) How is a sample related to a population? 2) Why is a sample used more often than a population? 3) What is the difference between a parameter and a statistic? 4) What are the two main branches of statistics?

True of False A statistic is a numerical value that describes a population characteristic? False A sample is a subset of a population. True It is impossible for the Census Bureau to obtain all the census data about the population of the United States. True Inferential statistics involves using a population to draw conclusions about a corresponding sample. False 10) A sample statistic will not changes from sample to sample. False

1.2

Section 1.2 Data Classification Qualitative data consist of attributes, labels, or nonnumerical entries. Quantitative data consist of numerical measurements or counts.

Suggested Retail Price Model Suggested Retail Price Accord Sedan $21,680 Civic Sedan $19,165

Height of hot air balloons quantitative Carrying Capacities of pickups quantitative Eye colors of models qualitative Student ID numbers quantitative Weights of infants at a hospital quantitative Species of trees in a forest qualitative Responses on an opinion poll qualitative Wait times at a grocery store quantitative

1.3

1.3 Data Collection and Experimental Design Observational Study, a researcher observes and measures characteristics of interest of a part of a population but does not change existing conditions. In an observational study a researcher does not influence the responses.

In an experiment , a treatment is applied to part of a population called a treatment group, and responses are observed. Another part of the population may be used as a control group , in which no treatment is applied. In many cases subjects in the control group are given a placebo (a fake treatment).

Example 1 and 2 for students on page 18

Three Key Elements of a good experiment: 1) Control 2) Randomization 3) Replication

A confounding variable occurs when an experimenter cannot tell the difference between the effects of different factors on the variable. Example: A coffee shop owner experiments by remodeling her shop using bright colors. A the same time, a shopping mall nearby has a grand opening.

Another factor that can affect experimental results is the placebo effect. The placebo effect occurs when a subject reacts favorably to a placebo when in fact that subject has been given a fake treatment. To help control or minimize the placebo effect, a technique called blinding can be used.

Replication is the repetition of an experiment under the same or similar conditions.

Blinding is a technique where the subjects do not know whether they are receiving a treatment or a placebo. In a double-blind experiment, neither the experimenter nor the subjects know if the subjects are receiving a treatment or a placebo. The experimenter is informed after all the data have been collected. This type of experiment design is preferred by researchers.

Randomization is a process of randomly assigning subjects to a different treatment groups.

A survey is an investigation of one or more characteristics of a population. Most often, surveys are carried out on people by asking them questions. The most common types of surveys are done by interview, Internet, phone, or mail. i.e. Mr. Curry’s survey on his web site

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1) What is the difference between an observational study and an experiment? In an experiment, a treatment is applied to part of a population and responses are observed. In an observational study, a researcher measures characteristics of interest of a part of a population but does not changes existing conditions.

2) What is the different between a census and a sampling 2) What is the different between a census and a sampling? A census includes the entire population; a sampling includes only a portion of the population.

3) What is the difference between a random sample and a simple random sample? In a random sample, every member of the population has an equal chance of being selected. In a simple random sample, every possible sample of the same size has an equal chance of being selected.

4) What is replication in an experiment. Why is replication important 4) What is replication in an experiment? Why is replication important? Replication is the repetition of an experiment under the same or similar conditions. Replication is important because it enhances the validity of results.

True or False. 5) A placebo is an actual treatment. False True or False? 5) A placebo is an actual treatment? False. Fake treatment 6)A double-blind experiment is used to increase the placebo effect? False. A double-blind experiment is used to decrease the placebo effect. 7) Using a systematic sample guarantees that members of each group within a population will be sampled? False. Using stratified sampling guarantees that members of each group within a population is sampled.

8) A census is a count of part of a population 8) A census is a count of part of a population. False a census is a count of an entire population. 9) The method of selecting a stratified sample is to order a population in some way and then select members of the population at regular intervals. False. That would be systematic. 10) To select a cluster sample, divide a population into groups and then select all of the members in at least one(but not all) of the groups. True

Observational Study or experiment. 11) in a survey of 177,237 U. S Observational Study or experiment? 11) in a survey of 177,237 U.S. adults, 65% said they visited the dentist in the last 12 months. Observational study

12) Researchers demonstrated in people at risk for increased cardiovascular disease that 2000 milligrams per day of acetyl-L carnitine over a 24- week period lowered blood pressure and improved insulin resistance. Experiment

Identifying sampling techniques Identifying sampling techniques. 23) Using random digit dialing, researchers call 1400 people and ask what obstacles (such as childcare) keep them from exercising. Simple random sampling 24) Chosen at random, 500 rural and 500 urban people age 65 or older are asked about their health and their experience with prescription drugs. Stratified

25) Questioning students as they leave a university library, a researcher askes 358 students about their drinking habits. Convenience sampling 26) After a hurricane, a disaster area is divided into 200 equal grids. Thirty of the grids are selected, and every occupied household in the grid in interviewed to help focus relief efforts on what residents require the most. Cluster

27) Chosen at random.