CJUS K300 1nd Edition Exam 1 Study Guide Lectures 1 5 Lecture 1 August 25 Simple Random Sample Steps Obtain a list of all members of the population Number all items participants on the list Decide on your desired sample size n Select numbers from a random number table or generator until desired sample size is obtained Systematic Random Sample Steps Obtain a list of all members of the population Number all items participants on the list Decide on your desired sample size n Select one random number from a random number generator Eg 10 Select every 10th number from the list until the desired sample size is obtained Random sampling is always Known Each persons probability is known ex 10 chance of being chosen Equal Each person has the same known probability of being selected Independent Each person has no effect on another or their chance of being selected Lecture 2 August 27 Levels of Measurement Nominal o All inclusive o Mutually exclusive each case must belong to only one group o No inherent order for the groups Ex Sex M F or F M the order it s presented makes no difference Ordinal o All inclusive o Mutually exclusive o Ordered but distance between two adjacent categories may vary Likert scale without numbers Interval and Ratio o All inclusive o Mutually exclusive o Ordered but there are equal distances or interval between any two adjacent categories Interval Likert scale with numbers below zero is arbitrary does not mean an absence ex Temperature Ratio Zero has a meaning which refers absence Lecture 3 September 3 Calculating rates divide the frequency by the number of people in the population f N Calculating standardized rates multiply each rate by either 10 100 1000 10 000 with the purpose of transforming your rated in to numbers which do not begin with a decimal Ratios are simply a means of comparing two entities Ex If there were 90 arrests for DUI and 30 for theft then the ratio to compare the two would be 3 1 Proportion divide the category frequency by the total n N Percent simply multiply the proportion by 100 Lecture 4 September 8 Range the difference between the least and the greatest value for a variable Example 10 9 3 11 4 13 o Range 13 3 or 10 points difference Mode the most frequently occurring value for a variable o Mathematically the value most likely to be picked at random from the data set o Bimodal two modes tri modal three modes no mode o Can be used with any level of measurement but doesn t always represent the data well Median the midpoint value in a rank ordered data set First rank order the data then determine the middle most value If there are three data points it s the number in the 3 rd position if there are four data points then the median is the value in the 2 5 th position meaning adding the two middle most points together and dividing by 2 Mean The average of the data set Adding all the data together and dividing it by the number of data points For population data sum of x N for sample data sum of x n Lecture 5 September 10 Variance A one number summary of how spread out the values for a variable are taking into account every value for the variable These formulas will be given to you on the exam but you should know how to calculate them make sure you review order of operation PEMDAS Variance for population data P E M D A S P Parenthesis E Exponents M D Multiplication and Division A S Addition and Subtraction Equation sheet will be given out before the exam DON T FORGET YOUR CALCULATORS