TERMS

• Census


  A survey conducted by including every element of the population
• Cluster


  A subgroup (usually geographical) of the population that is representative of the population
• Cluster sampling


  A sampling technique in which the population is divided into clusters and a sample is chosen from one or a few clusters
• Continuous variable


  A (quantitative) variable that can assume any numerical value over a certain interval or intervals
• Control group


  The group of elements on which no condition is imposed
• Convenience sample


  A sample that includes the most accessible members of the population
• Cross-section data


  Data collected on different elements at the same point in time or for the same period of time
• Data or data set


  Collection of observations or measurements on a variable
• Descriptive statistics


  Methods for organizing, displaying, and describing data using tables, graphs, and summary measures
• Designed experiment


  A study in which the experimenter controls the assignment of elements to different treatment groups
• Discrete variable


  A (quantitative) variable whose values are countable
• Double-blind experiment


  An experiment in which neither the doctors (or researchers) nor the patients (or members) know to which group a patient (or member) belongs
• Element or member


  A specific subject or object included in a sample or population
• Experiment


  A method of collecting data by controlling some or all factors
• Inferential statistics


  Methods that help make decisions about a population based on sample results
• Judgment sample


  A sample that includes the elements of the population selected based on the judgment and prior knowledge of an expert
• Nonrandom sample


  A sample drawn in such a way that some members of the population have no chance of being selected in the sample
• Nonresponse error


  The error that occurs because many of the people included in the sample do not respond
• Nonsampling or systematic errors


  The errors that occur in the collection, recording, and tabulation of data
• Observation or measurement


  The value of a variable for an element
• Observational study


  A study in which the assignment of elements to different treatments is voluntary, and the researcher simply observes the results of the study
• Population or target population


  The collection of all elements whose characteristics are being studied
• Qualitative or categorical data


  Data generated by a qualitative variable
• Qualitative or categorical variable


  A variable that cannot assume numerical values but is classified into two or more categories
• Quantitative data


  Data generated by a quantitative variable
• Quantitative variable


  A variable that can be measured numerically
• Quota sample


  A sample selected in such a way that each group or subpopulation is represented in the sample in exactly the same proportion as in the target population
• Random sample


  A sample drawn in such a way that each element of the population has some chance of being included in the sample
• Randomization


  The procedure in which elements are assigned to different (treatment and control) groups at random
• Representative sample


  A sample that contains the characteristics of the population as closely as possible
• Response error


  The error that occurs because people included in the survey do not provide correct answers
• Sample


  A portion of the population of interest
• Sample survey


  A survey that includes elements of a sample
• Sampling frame


  The list of elements of the target population that is used to select a sample
• Sampling or chance error


  The difference between the result obtained from a sample survey and the result that would be obtained from the census
• Selection error


  The error that occurs because the sampling frame is not representative of the population
• Simple random sampling


  If all samples of the same size selected from a population have the same chance of being selected, it is called simple random sampling
• Statistics


  Science of collecting, analyzing, presenting, and interpreting data and making decisions
• Stratified random sampling


  A sampling technique in which the population is divided into different strata and a sample is chosen from each stratum
• Stratum


  A subgroup of the population whose members are similar with regard to the possession of a characteristic