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# Prob & Stats Ch.1

### Chapter 1 Vocab and Concepts

Term | Definition |
---|---|

Variable | a characteristic or attribute that can assume different values |

Data | the values (measurements or observations) that the variables can assume |

Random Variables | Variables whose values are determined by chance |

Data Set | A collection of data values |

Data Value (Datum) | Each value in a data set |

Statistics | the science of conducting studies to collect, organize, summarize, analyze, and draw conclusions from data |

Descriptive Statistics | consists of the collection, organization, summarization, and presentation of data |

Inferential Statistics | consists of generalizing from samples to populations, performing estimations and hypothesis tests, determining relationships among variables, and making predictions |

Probability | the chance of an event occurring |

Population | consists of all subjects that are being studied |

Sample | a group of subjects selected from a population |

Hypothesis Testing | a decision-making process for evaluating claims about a population based on information obtained from samples |

Qualitative Variables | variables that can be placed into distinct categories, according to some characteristic or attribute |

Quantitative Variables | numerical variables that can be ordered or ranked |

Discrete Variables | variables which assume values that can be counted |

Continuous Variables | variables which can assume an infinite number of values between any two specific values. Obtained by measuring and often include fractions and decimals |

Measurement Scales | four common types of these scales are nominal, ordinal, interval, and ratio |

Nominal Level of Measurement | classifies data into mutually exclusive (nonoverlapping), exhausting categories in which no order or ranking can be imposed on the data |

Ordinal Level of Measurement | classifies data into categories that can be ranked; however, precise differences between the ranks do not exist |

Interval Level of Measurement | ranks data, and precise differences between units of measure do exist; however there is no meaningful zero |

Ratio Level of Measurement | possesses all the characteristics of interval measurement, and there exists a true zero. In addition, true ratios exist when the same variable is measured on two different members of the population |

Four Basic Sampling Techniques | Random, Systematic, Stratified, & Cluster |

Random Samples | selected by using chance methods or random numbers |

Systematic Samples | obtained through numbering each subject of the population and then selecting every nth subject |

Stratified Samples | obtained by dividing the population into groups (called strata) according to some characteristic that is important to the study |

Cluster Samples | the population is divided into groups called clusters by some means such as geographic area or schools in a large school district, etc. |

Convenience Sample | uses subjects that are convenient |

Observational Study | the researcher merely observes what is happening or what has happened in the past and tries to draw conclusions based on these observations |

Experimental Study | the researcher manipulates one of the variables and tries to determine how the manipulation influences other variables |

Quasi-Experimental Study | when researchers use already intact groups if random assignment is not possible |

Independent (Explanatory) Variable | the variable being manipulated in an experimental study |

Dependent (Outcome) Variable | the resultant variable of an experimental study |

Treatment Group | the group that receives specific treatment in an experimental study |

Control Group | the group that receives no treatment in an experimental study |

Hawthorne Effect | discovered in 1924 when researchers found that the subjects who knew they were participating in an experimental study actually changed their behavior in ways that affected its results |

Confounding Variable | variable that influences the dependent/outcome variable but was not separated from the independent variable |

Define statistics | the science of conducting studies to collect, organize, summarize, analyze, and draw conclusions from data |

Three examples of how statistics is used in everyday life. | 1) Fields of human endeavor (2) Analyze results of a survey (3) Tool in scientific research to make decisions based on controlled experiments (4) Operations research, quality control estimation, & predictions |

3 reasons to study statistics | (1) Understand statistical studies (2) Conduct research, design experiments, make predictions, and communicate results (3) Become a better consumer |

Branch areas of statistics | Differential and Inferential. Differential statistics deals with the collection, organization, summarization, and presentation of data, whereas inferential statistics deals with generalizing from samples to populations and making predictions/inferences. |

Examples of Variables | Qualitative - gender, eye color, etc. Quantitative - age, height, weight. Discrete - #'s of something. Continuous - often decimals obtained by measuring. |

Examples of each of the levels of measurement | Nominal - Gender, Zip code, Eye color Ordinal - Competition rankings, a person's build, letter grades Interval - |

Created by:
tyjocun