Exam 1 Study Guide

Exam 1 Study Guide - Exam 1 Study Guide BY SAMANTHA RUDA...

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Exam 1 Study Guide B Y S AMANTHA R UDA D ESCRIBING Y OUR D ATA (C HAPTER 4) T OPIC 1- I NTRODUCTION TO S TATISTICS Descriptive vs. Inferential Statistics: o Descriptive summarizes the values of a data set by using charts, graphs, averages, and tables o Inferential makes generalizations based on the descriptive statistics of our sample data Population -group of elements for which understanding is desired Process - set of conditions that repeatedly come together to transform inputs or outcomes Sample - subset of a population or process Parameter - number that summarizes some aspect of a population or process – descriptive measure of a population Statistic - number that summarizes some aspect of a sample – descriptive measure of a sample Sampling Error – difference between the result of a sample and the corresponding result of a census Statistical Inference - using sample information to learn about a population or a process Statistical Variable - single characteristic of any object or event Qualitative vs. Quantitative Data o Qualitative (categorical/nominal) data is the data values that are places into classes and have no natural ordering, valid computation: count or proportion of observations in a given category, category or ranks Gender, political party Can’t have averages or differences
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o Quantitative data is the data values that are measured by meaningful (not arbitrary) numbers that tell how much or how many, valid computation: count or proportion of observations in a given category, numerical or measurements Family Size, Length of Employment T OPIC 2- V ISUALIZING D ATA W ITH O NE V ARIABLE Frequency - is the number of times a given datum occurs in a data set Relative Frequency – compares each class interval to the total number of items; the fraction of times an answer occurs. To find the relative frequencies, divide each frequency by the total number of students in the sample, can be fractions, decimals, or percents The only difference between a frequency histogram and a relative frequency histogram is that the vertical axis uses relative or proportional frequency instead of simple frequency Cumulative Relative Frequency Distributions (histograms) the accumulation of the previous relative frequencies. To find the cumulative relative frequencies, add all the previous relative frequencies to the relative frequency for the current row. Symmetric vs. Non-symmetric Distribution Shapes
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This note was uploaded on 01/31/2010 for the course SCM 382867 taught by Professor Marilynblanco during the Spring '08 term at Penn State.

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Exam 1 Study Guide - Exam 1 Study Guide BY SAMANTHA RUDA...

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