MGSC 291 EXAM 1

MGSC 291 EXAM 1 Statistics - ✔✔The methodology of extracting useful information from a data set What are the two branches of statistics? - ✔✔Descriptive and Inferential Descriptive Statistics - ✔✔refers to the s ...

MGSC 291 EXAM 1 Statistics - ✔✔The methodology of extracting useful information from a data set What are the two branches of statistics? - ✔✔Descriptive and Inferential Descriptive Statistics - ✔✔refers to the summary of a data set in the form of tables, graphs, or the calculation of numerical measures -collecting, organizing, and presenting the data Inferential Statistics - ✔✔refers to extracting useful information from a sample to draw conclusions about a population Population - ✔✔Consists of all items of interest Sample - ✔✔A subset of the population of interest -A good sample is representative of the population Cross-sectional Data - ✔✔Recording a characteristic of many subjects at the same point in time, or without regard to differences Time Series Data - ✔✔Contains values of a characteristic of a subject over time Qualitative Variable - ✔✔Uses labels or names to identify the distinguishing characteristic of each observation Quantitative Variable - ✔✔Assumes meaningful numerical values and can be further categorized as either discrete or continuous Discrete Variable - ✔✔Something you can count Continuous Variable - ✔✔Can take on an infinite number of values -things that are measured- time, distance, etc. All data measurements can be classified into one of what four major categories - ✔✔-Nominal Scale -Ordinal Scale -Interval Scale -Ratio Scale Nominal Scale - ✔✔Data is simply categorized- not ordered -least sophisticated Ordinal Scale - ✔✔Data categorized and ranked- ordered Interval Scale - ✔✔Data may be categorized and ranked with respect to characteristic or trait -differences between scale values are meaningful -no true zero Ratio Scale - ✔✔Meaningful ratios can be calculated with values -most common and strongest level of measurement -true zero -Ex: weight, time, distance, sales, profits, inventory levels Which two types of data measurements are Qualitative? - ✔✔-Nominal -Ordinal Which two types of data measurements are Quantitative? - ✔✔-Interval -ratio For qualitative data, a frequency distribution does what? - ✔✔Groups data into categories and records the number of observations that fall into each category For qualitative data, a relative frequency does what? - ✔✔shows the proportion (or the fraction) of the observation in each category Graphically, frequency distribution for qualitative data can be shown how? - ✔✔-Pie Chart -Bar Chart For quantitative data, a frequency distribution groups data into intervals called what? - ✔✔Classes -then records the number of observations that falls into each class -the number of classes usually ranges from 5-20 Approximating the Class Width - ✔✔Largest Value - Smallest Value / # of Classes Cumulative Frequency Distribution - ✔✔Records the number of observations that falls below the upper limit of each class Relative Frequency Distribution - ✔✔Identifies the proportion (or the fraction) of observations that falls into each class Cumulative Relative Frequency Distribution - ✔✔Shows the proportion (or the fraction) of observations that falls below the upper limit of each class Histograms and Polygons are graphical representations of what? - ✔✔Frequency or relative frequency distributions -histograms place a class limit -polygons- use connected dots An ogive is a graphical representation of what? - ✔✔A cumulative frequency or cumulative relative frequency distribution Skewed Distribution - ✔✔-Positively- data forms a long, narrow, tail to the right -Negatively- data forms a long, narrow, tail to the left Symmetric Distribution - ✔✔Mirror image on both sides of center Stem-and-Leaf Diagram - ✔✔Another visual method to display quantitative data -Stem= left most digit -Leaf= last digit -When ordering leaves that are negative, order them high to low Scatter Plot - ✔✔A graphical tool that helps in determining whether or not two quantitative variables are related in some systematic way What is the most widely used measure of central location? - ✔✔Mean (average) What is a weakness of the mean? - ✔✔It is sensitive to outliers Median - ✔✔The middle value of a data set -Also a measure of central location -Not sensitive to outliers Mode - ✔✔The value(s) in the data set that occurs with the most frequency -There can be no mode, one mode, or multiple modes Weighted Mean - ✔✔Data already grouped -Ex: computing a course grade Range - ✔✔Maximum value - minimum value -Simplest measure -Focused on the extreme measure Mean Absolute Deviation (MAD) - ✔✔An average of the absolute difference of each observation from the mean -Denominated in the same unit as the original data -Cannot be negative Percentiles - ✔✔Provide detailed information about how the data are spread over the interval from the smallest value to the largest value - 25th, 50th, and 75th percentiles are respectively referred to as Q1, Q2, and Q3 Coefficient of Variation (CV) - ✔✔A relative measure of dispersion -Allows comparisons of variability between data sets with different means or different units of measurement (because CV is unit-less) Z-Score - ✔✔Indicates a value's distance from the mean in terms of number of standard deviation -Often used to denote relative location The dispersion measurement that is computed as the average of the sum of the squared difference from the mean is the? - ✔✔Variance Probability - ✔✔A numerical value that measures the likelihood that an event occurs Probabilities are between? - ✔✔Zero and one -Probability of zero indicates impossible events -Probability of one indicates definite events Experiment - ✔✔A process that leads to one of several possible outcomes Sample Space - ✔✔Lists all possible outcomes of an experiment -Denoted s Event - ✔✔Any subset of outcomes of an experiment -Called a simple event if it contains a single outcome Events are considered to be either..? - ✔✔Exhaustive or Mutually Exclusive Exhaustive Events - ✔✔List all possibilities in the sample space Mutually Exclusive Events - ✔✔Outcomes have no overlap/ nothing in common Venn Diagram - ✔✔Can be used to represent the sample space The union of two events - ✔✔The event consisting of all outcomes A or B A U B The intersection of two events - ✔✔Consists of all simple events in both A and B A ∩ B Complement of an area - ✔✔Consists of all simple events in the same space, s, that are not in A A^c Subjective Probability - ✔✔Draws on personal and subjective judgement What are the two types of objective probability? - ✔✔Empirical and Classical Empirical Probability - ✔✔The relative