Chapter 2 Notes
Chapter 2 Notes Soc 301-01
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This 6 page Class Notes was uploaded by Tamar Noisette (Notetaker) on Wednesday September 9, 2015. The Class Notes belongs to Soc 301-01 at La Salle University taught by Caitlin Taylor in Fall 2015. Since its upload, it has received 83 views. For similar materials see Social Stats I in Sociology at La Salle University.
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Date Created: 09/09/15
Chapter 2 Notes Means to an End Computing and Understanding Averages Statistics for People Who Think They Hate Statistics pages 2135 moter 2 Obiectiveg 0 Understanding measures of central tendency 0 Computing the mean for a set of scores 0 Computing the mode and the median for a set of scores 0 Selecting a measure of central tendency After data are collected the first step is usually to organize the info using simple indexes to describe data The easiest way to do that is through computing averages c There are many different types of averages o Avera e Exam le 1 Averages can also be known as measures of central tendency in which there are 3 mean median and mode Computinq the Mean 0 Exam le 3 m m 3 a Formula for computing the meamp o The X the line over it is the X bar and it represents the mean value c The Greek letter Sigma that is in the numerator section of the equation is the summation sign which means to add whatever follows it o The X next to the Sigma represents the individual score in the group of scores that is to be added 0 The n represents the amount of values in the sample 0 Steps to Compute the mean 1 List the entire set of values Xs 2 Add up the values to get the sum 3 Divide the sum by the number of values that are present Thinqs to Remember 0 The mean is sometimes represented by the letter M o It can also be referred to as the typical average or the most central score pExam Ia In addition to that the formula also include a small r vvhich represents the sample size that the mean is computed for o A large N represents the population size but in some texts there is no distinction made between the tvvo o The sample mean is the measure of central tendency that best reflects the population mean i Picture a seesaw the fulcrum of the seesavv represents the mean and the other sides that balance each other out represent the other values on either side of the mean It The mean is sensitive to extreme scores valoesoombers that are much brgger or smafferfhan the others around as the set and can end up improperly representing a set of scores and as a result can become less useful in terms of measure of central tendency o Another name for the mean is the arithmetic mean The arithmetic mean can also be defined as the point about which the sum of deviations is equal to zero Example If you have scores like 34 and 5 the mean is 4 the sum of deviations about the mean 10 and 1 is 0 Computing the Weiqhted Mean A weighted mean can be computed by multiplying the value by the frequency of its occurrence m to findinq the weiqhted mean 1 List all the sample values that are being used to find the mean 2 List the number of times the value occurs frequency 3 Multiply the value by the number of time the value the value occurs Value x Frequency 4 Divide it by the total frequency M In Basic statistics there is an important distinction made between values that are associated with samples a part of a population and populations Roman letters are used for a sample statistic the mean of a sample and Greek letters are used for a population parameter mean of a population m Computinq the Median The median is the average as well but it s a different type Median There is no rigid formula for finding the median m for findinq the Median 1 Set up the values in order from highest to lowest or lowest to highest 2 Find the score that falls in the middle m It is much easier to find the median in a set that has an odd amount of values In the event where there is an even set of values the median will be the mean of the two middle most values Percentile points o The median can be considered as a better method for finding the average because unlike the mean it is not sensitive to extreme scores 0 BUT It is suggested that one computes both the mean and median to see which one works best for a set of data that has one or more extreme scores 0 The median is sometimes represented by the symbol of Med or Mdn Thinqs to remember about the median o The mean is the middle point of a set of values but the median is the middle point of a set of cases 0 Extreme scores aka don t matter when it comes to the median Computing the Mode Mode 0 m to findinq the mode 1 List each value in the distribution once 2 Tally up the number of times each value occurs 3 The one that occurs the most is the mode Q m 3 i o If every value in a distribution has the same number of occurrences then there is no mode 0 If more than one value appears with an equal frequency then the distribution is multimodal Q m 3 5 When to use what Conclusion Which measure of central tendency mean median or mode you use depends on the type of data that you re describing 0 Use the m when there is qualitative categorical or nominal data present when values can only fit into one class Q m 3 5 0 Use the Median when there is guantitative data present when there are extreme scores and you don t want the average to be off Q m 3 5 0 Use the Mode when there is guantitative data present as well when there is data that do not include extreme scores and aren t categorical Works Cited Salkind Neil J quotChapter 2 Means to an End Computing and Understanding Averages Statistics for People Who think They Hate Statistics Thousand Oaks CA SAGE Publications 2011 2135 Print
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