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# Chapters 1-2 Stats 240

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This 4 page Class Notes was uploaded by Lauren Prentis on Monday February 2, 2015. The Class Notes belongs to Stats 240 at University of Massachusetts taught by Dr. Jeneralczuk in Fall. Since its upload, it has received 250 views. For similar materials see Introduction to Statistics in Statistics at University of Massachusetts.

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Date Created: 02/02/15

Chapter 1 Introduction to Statistics 240 11 Statistics and Types of Statistics 0 Common usage Numerical Facts 0 The science that deals With the collection classification analysis and interpretation of information or data 0 Art and science of learning Tvnes of Statistics Descriptive Statistics methods for organizing displaying describing data by using tables and graphs ie how much money companies spend on ads in 2010 Inferential Statistics methods that use sample results to help make decisions or predictions about a population tv commercial and holiday shopping 12 Population Versus Sample Population consists of all elements individuals items or objects the population being studied is referred to as the target population ie a census is a count of the population Sample a portion of the population selected for study sample size does not depend on population size 0 Representative Sample represents all aspectscharacteristics of the population as closely as possible 0 Random Sample the sample is pulled in a way that gives each aspectcharacteristic of the population a fair chance of being selected for the poll 0 Simple random sampling all samples of the same size selected from a population have the same chance of being selected 0 Sampling Without replacement the selected element is not replaced in the population each time one is selected 0 Sampling With replacement each time an element from the population is selected it is put back before choosing another element 13 Basic Terms Elementmember is a specific subject of object about Which the information is collected names of companies states etc Variable is a characteristic under study that assumes different values for different elements Observationmeasurement the value of a variable for an element Data set a collection of observations on one or more variables 14 Types of Variables Categorical Variable a variable that cannot assume a numerical value gender opinions preferences 0 Quantitative Variable can be measured numerically 0 Discrete Variables variables that assume countable values usually With no units can assume only certain values With intermediate values 0 Continuous Variables variables that can assume any numerical value over a certain interval usually With units 15 CrossSection Versus TimeSeries Data 0 CrossSection Data data collected on different elements at the same point in time or for the same period of time 0 TimeSeries Data data collected on the same element for the same variable at different points in time or for different periods of time 16 Sources of Data 0 Private publications 0 Internal sources 0 External sources 0 Surveys 0 Experiments 17 Summation Notation 0 Used to denote the sum of values based on how many variable are present Chapter 2 21 Organizing and Graphing Qualitative Data 0 Raw data data recorded in the sequence in which they are collected and before they are processed or ranked are called raw data 0 Ungrouped data contains information on each member of a sample or population individually 0 Frequency distribution exhibits how the frequencies are distributed over various categories known as frequency distribution tablesfrequency table 0 Calculations 0 Relative frequency of a category Frequency of that categorySum of all frequencies 0 Percentage relative frequency 100 0 Graphical Presentation of Qualitative Data 0 Bar GraphChart categories on Xaxis frequency on yaXis One bar for each category and the height of each bar corresponds with a frequency 0 Pie Chart a circle divided into portions that represent the relative frequencies or percentages of a population or a sample belonging to different categories is called a pie chart 22 Organizing and Graphing Quantitative Data 0 Frequency Distributions 0 Class the interval that all values fall within the upper and lower limits 0 Frequency Distribution lists all classes and the number of values that belong to each class Data presented in the form of a frequency distribution are called grouped data 0 Class Boundary is given by the midpoint of the upper limit of one class and the lower limit of the next class 0 Class widthsize the difference between the two boundaries of a class I Approximate class width largest value smallest value of classes 0 Class midpointmark is obtained by dividing the sum of the two limits or the two boundaries of a class by 2 39 Class midpoint or mark lower limit Upper limit2 0 Relative Frequency and Percentage Distributions 0 Relative Frequency of a class frequency of that classSum of all frequencies 0 Graphing Grouped Data 0 Polygon a graph formed by joining the midpoints of the tops of successive bars in a histogram with straight lines 0 Shapes of Histograms O Symmetric is identical on both sides of its central point 0 Skewed is nonsymmetric 39 Skewed to the right has a longer tail on the right side 39 Skewed to the left has a longer tail on the left side 0 Uniform or Rectangular has the same frequency for each class 23 Cumulative Frequency Distributions 0 Cumulative Frequency Distribution gives the total number of values that fall below the upper boundary of each class 0 Ogive is a curve drawn for the cumulative frequency distribution by joining with straight lines the dots marked above the upper boundaries of classes at heights equal to the cumulative frequencies of respective classes 24 Stemandleaf plot displays 0 Stem and leaf plot each value is divided into two portions a stem and a leaf The leaves for each stem are shown separately in display 25 Dot plots 0 Outliers or Extreme Values are very large or very small relative to the majority of the values in a data set

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