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# Prob.Stat. Ch.1/14

### Ch.1 14.1 14.2 Margin of Error

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

Variable | a characteristic or attribute that can assume different |

Data | the values the variables assume |

Random Variable | variables whose values are determined by chance |

Data Set | a collection of data values |

Data Value - Datum | each value of the data set |

Probability | the chance of an event occurring |

Population | all the subjects that are being studied |

Sample | a group of subjects selected from a population |

Hypothesis Testing | decision-making process for evalutating claims about a population |

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

3 examples of how statistics is used in everyday life | gambling, sports, public health |

3 reasons to study statistics | Read and understand the various statistical studies performed in your fields You may be called on to conduct research in your field Can become better consumers and citizens |

Descriptive | consists of collection, organization, summarization, and presentation of data Ex. U.S. population senses |

Inferential | generalizing from samples to populations, performing estimations and hypothesis tests, determining relationships among variables, and making predictions. Ex. gambling |

Quantitative | numerical and can be ordered or ranked Ex. age, height, weight |

Qualitative | can be placed into distinct categories but not ranked Ex. gender, color, religion |

Discrete | quantitative- variables that assume values that can be counted Ex. # of children, # of students |

Continuous | quantitative- variables that can assume an infinite number values between any 2 specific values. Ex. capacity |

Boundaries | Ex. 18 17.5 - 18.5 4.68 4.675 - 4.685 |

Nominal | no order or rank can be imposed on the data Ex. gender, zip code |

Ordinal | precise differences between ranks do not exist Ex. rating public speakers, rating floats (1st, 2nd, 3rd) |

Interval | precise differences between units of measure; no meaningful zero Ex. IQ test, Temperature |

Ratio | same as interval but with a meaningful zero Ex. height, weight |

2 purposes of data collection | to describe situations or events to help people make better decisions before acting |

3 ways to collect data | surveys, survey records, direct observation |

Random Sampling | putting random numbers in a hat and having people pull them out randomly |

Systematic Sampling | every fourth person being selected from a group |

Stratified Sampling | splitting people into groups by gender and only taking 10 from each group |

Cluster Sampling | characterizing people into 5 groups and taking all the people of 2 of these groups |

Telephone survey | advantage-people can be more candid disadvantage- not all people can be surveyed |

Mailed survey | advantage- can cover a wider geographic area disadvantage- low number of responses |

Personal interview | advantage- can obtain in-depth response disadvantage- more costly |

Observational- Examples | Age of motorcycle owners |

Experimental- Examples | Type of instruction affects the number of sit-ups |

Observational- advantages and disadvantages | Natural setting; can be done in dangerous situations; can be done using variable that can't be manipulated Definite cause and effect can't be found; expensive and time consuming; may have inaccuracies in measurements |

Experimental- advantages and disadvantages | Researcher can decide how to select and group subjects; can control the manipulated variable Unnatural setting; Hawthorne Effect; Confounding variable |

Independent Variables | the variable that is being manipulated by the researcher |

Dependent Variables | the variable that is being studied to see if it changes due to the manipulated |

5 uses of statistics | To describe data; To compare two or more data sets; To determine if variables are related; To test hypothesis; To make estimates about population variances |

7 misuses of statistics | Suspect samples; Ambiguous averages; Changing the subject; Detached statistics; Implied connections; Misleading graph; Faulty survey |

Things that make bad questions | Biased questions; Confusing words; Double-barreled questions; Double negatives in a question; Improper ordering of questions |

Problems of getting random samples and systematic | being able to number the whole population |

true vs. quasi experiments | True- sample selected randomly Quasi- using intact group because separation is not possible |

Confounding Varibles | a variable that influences the results of dependent but cannot be separated from the independent |

Hawthorne Effect | the subject knows that they are participating and purposely change their behavior in ways that it affects the results |

Control Group | the group that does not receive the treatment |

Treatment group | the group that receives specific treatment |

Margin of Error | +/- 1/(sq rt n) |

MoE Interval | The percent +/- the margin of error |

Biased question | a question that leads people to respond a certain way changing the results of the study |

Sequential Sampling | used in quality control |

Double sampling | Giving a huge population a questionnaire to find out who is qualified for the actual study |

Multistage sampling | uses multiple types sampling |

Created by:
ATocci96