Summary Statistics ch 4 Exam Questions And Answers ( Verified And Updated )

Summary Statistics ch 4 Exam Questions And Answers ( Verified And Updated ) What are three main measures of central location? - answer1) Mean 2) Median 3) Mode What is a mean? - answerthe gravitational center of the distribution What is a mode? - answerthe most frequently occurring value in the data ==> usually only used in large data sets with many repeating values What is the median? - answerthe central value in the order array of the data Describe the notation for: 1) sample size 2) the variable (i.e. age) 3) the value of individual i for variable X 4) sum of all values - answer1) n 2) X 3) xi <==i is a subscript 4) Capital sigma What is the "sample mean" ? (2 definitions) - answer1) traditional measure of central location (of the sample) 2) the balancing point of distribution (see Biostatistics Study Chart and Diagrams) ==> it is the arithmetic average = sum of values and divide by n What is the notation for the sample mean? Write out the equation. - answer"xbar" See Biostatistics Study Charts and Diagrams The value of the mean from a random sample observations can be used to predict the _________ ____________ - answerpopulation mean What is the population mean? ==> it is also known as ____ _____? - answerThe mean of the true population (what we are trying to study) ==> expected value What is the notation for the population mean? Write out the equation. - answer"mu" See Biostatistics Study Charts and Diagrams What is the median? - answerthe value with a depth of (n+1)/2 when n is even, averge the two values that straddle a depth of (n+1)/2 EXAM: What must be TRUE in order to calculate the median? - answerthe values must be ORDERED first Mean vs Median: Why is each one better than the other? When is it best to use each one? - answerMean ==> more efficient than the median in describing a distribution's center b/c it makes use of the quantitative info <== best to use if w/ normal distribution Median ==> more ROBUST b/c leas influenced by outliers and skews What is a mode - answer What is the mode of {4, 6, 7, 8}? Explain. - answerThere is no mode b/c none of the numbers are repeating. What is the effect on the mean, median, and mode when there is a symmetrical distribution? - answermean = median = mode (not sure on the mode part) What is the effect on the mean, median, and mode when there is a positive skew? Explain. - answermean > median