Chapter 1

__________ statistics consists of organizing and summarizing information collected, while __________ statistics uses methods that generalize results obtained from a sample to the population and measure the reliability of the results.

Descriptive, inferential

Sources of Bias in Sampling

Sampling Bias Nonresponse Bias Response Bias

Why is simple random sampling used?

Simple random sampling is used to let chance of randomness happen.

What does it mean when sampling is done without replacement?

The individual who is selected is removed from the population and cannot be chosen again.

____________ are the characteristics of the individuals of the population being studied.

Variables

Experiment

a controlled study conducted to determine the effect varying one or more explanatory variables or factors has on a response variable

Data

a fact or proposition used to draw a conclusion or make a decision

Census

a list of all individuals in a population along with certain characteristics of each individual

Frame

a list of all the individuals within the population

Parameter

a numerical summary of a population

Statistic

a numerical summary of a sample

Statistic

a numerical summary of a sample taken from a population

Individual

a person or object that is a member of the population being studied

Experimental Unit

a person, object, or some other well-defined item upon which a treatment is applied

Inferential Statistics

a process in which generalizations about a population are made on the basis of results obtained from a sample

Continuous Variable

a quantitative variable that has an infinite number of possible values that are not countable

Discrete Variable

a quantitative variable that has either a finite number of possible values or a countable number of possible values

Convenience Sampling

a sample in which the individuals are easily obtained and not based on randomness

Sample

a subset of a population that is being studied

Approach

a way to look at and organize a problem so that it can be solved

Determine whether the quantitative variables are discrete or continuous. a) The number of heads obtained after flipping a coin five times. b) The number of cars that arrive at a McDonald's drive-thru between 12:00 p.m and 1:00 p.m c) The distance a 2012 Toyota Prius can travel in city driving conditions with a full tank of gas.

a) Discrete We can count the number of heads obtained. b) Discrete We find its value by counting cars. c) Continuous We measure the distance.

Determine whether the following variables are qualitative or quantitative. a) Gender b) Temperature c) Number of days during the past week that a college student studied d) Zip Code

a) Qualitative It allows researchers to categorize individuals as male or female. b) Quantitative It is numeric and operations such as addition and subtraction provide meaningful results. c) Quantitative It is numeric and operations such as addition and subtraction provide meaningful results. d) Qualitative It categorizes a location. Even though they are numeric, adding or subtracting zip codes does not provide meaningful results.

Qualitative (Categorical) Variables

allow for classification of individuals based on some attribute or characteristic

Open Questions

allows the respondent to choose his or her response

Matched-Pairs Design

an experimental design in which the experimental units are paired up

Lurking Variable

an explanatory variable that was not considered in a study, but that affects the value of the response variable in the study

Placebo

an innocuous medication, such as a sugar tablet, that looks, tastes, and smells like the experimental medication

Treatment

any combination of the values of the factors

Variable

characteristics of an element

Descriptive Statistic

consist of organizing and summarizing data and is described through numerical summaries, tables, and graphs

Types of Observational Studies

cross-sectional studies case-control studies cohort studies

Qualitative Variables

describe an attribute or characteristic of the individual that allows researchers to categorize the individual

Descriptive Statistic

describes the results of the sample without making any general conclusions

Designing an Experiment

describing the overall plan in conducting the experiment

Fill in the blank. A variable is ______________ if its value results from counting. A variable is ________________ if its value is measured.

discrete, continuous

Population

entire group to be studied

Nonresponse Bias

exists when individuals selected to be in the sample who do not respond to the survey have different opinions from those who do

Response Bias

exists when the answers on a survey do not reflect the true feelings of the respondent

Cohort Studies

identifies a group of individuals to participate in the study (the cohort) then are observed over a long period of time

Simple Random Sampling

if every possible sample of size has an equally likely chance of occurring

Ratio Level of Measurement

if it has the properties of the interval level of measurement and the ratios of the values of the variable have meaning

Ordinal Level of Measurement

if it has the properties of the nominal level of measurement, however the naming scheme allows for the values of the variable to be arranged in a ranked or specific order

Interval Level of Measurement

if it has the properties of the ordinal level of measurement and the differences in the values of the variable have meaning

Bais

if the results of the sample are not representative of the population

Nominal Level of Measurement

if the values of the variable name, label, or categorize

Fill in the blank. A(n) __________ is a person or object that is a member of the population being studied.

individual

Case-Control Studies

individuals who have certain characteristics may be matched with those who do not

Observational Study

measures the value of the response variable without attempting to influence the value of either the response or explanatory variables

Descriptive Statistic

methods for summarizing the data

Inferential Statistics

methods of making decisions of predictions about a population based on data obtained from a sample of the population

Double-Blinding Experiments

neither the experimental nor the researcher in contact with the experimental unit knows which treatment the experimental unit is receiving

Quantitative Variables

numerical summaries such that arithmetic operations can be performed on the values of the variable

Cross-Sectional Studies

observational studies that collect information about individuals at a specific point in time or over a very short period of time

Continuous Data

observations corresponding to a continuous variable

Discrete Data

observations corresponding to a discrete variable

Qualitative Data

observations corresponding to a qualitative data

Quantitative Data

observations corresponding to a quantitative data

Cluster Sampling

obtained by selecting all the individuals within a randomly selected collection group of individuals

Systematic Sampling

obtained by selecting the nth individual from the population

Stratified Sample

obtained by separating the population into non-overlapping groups called strata and then obtaining a simple random sample from each stratum

Replication

occurs when each treatments is applied to mote than one experimental unit

Confounding

occurs when the effects of two or more explanatory variables are not separated

Completely Randomized Design

one in which each experimental unit is randomly assigned to a treatment

A(n) __________ is a numerical summary of a population.

parameter

Quantitative Variables

provide numerical measure of individuals

Fill in the blank. Variables that are nominal or ordinal are ________________ variables. Variables that are interval or ratio are ________________ variables.

qualitative, quantitative

Blinding

refers to nondisclosure of the treatment an experimental unit is receiving

Retrospective

require individuals to look back in time or require researchers to look at existing records

Closed Question

requires the respondent to choose from a list of predetermined responses

Non-Sampling Errors

result from under coverage, nonresponse bias, response bias or data-entry error

Sampling Error

results from using a sample to estimate information about a population

Control Group

serves as a baseline treatment that can be used to compare to other treatments

A(n) __________ is a numerical summary of a sample.

statistic

Variables

the characteristics of the individuals within the population

Single-Blind Experiments

the experimental units (or subjects) does not know which treatment he or she is receiving

Anecdotal

the information being conveyed is based on casual observation, not scientific research

Data

the list of observed values for a variable

Random Sampling

the process of using chance to select individuals from a population to be included in the sample

Statistics

the science of collecting, organizing, summarizing, and analyzing information to draw conclusions or answer questions

Sampling Bias

the techniques used to obtain the sample's individuals tends to favor one part of the population over another

Countable

the values result from counting

Inferential Statistics

uses methods that take a result from a sample, extend it to the population, and measure the reliability of the source