chapter 3

• add data values and divide by total number of data values

  mean
• the middle of the data

  median
• median is a resistant measure of data
• is mean effected by outliers?

  no
• if a graph is symmetric, then mean equals median
• if a graph is right skewed then mean is greater than median
• if a graph is left skewed then mean is less than median
• the value that appears the most frequently

  mode
• one mode = unimodal
• two modes = bimodal
• more than two modes = multimodal
• maximum value - minimum value

  range
• variability exists when some values are different from the mean
• if the SD is a small value, that means there is little variability in the data set
• if the SD is a large value, that means there is a lot of variation in the data set
• What measure of center should be used when the data is abnormally distributed?

  median
• what measure of center should be used when the data is normally distributed?

  mean
• Empirical rule:

  about 68 percent of the data lies within 1 SD of the mean

  about 95 percent of the data lies within 2 SD of the mean

  about 99.7 percent of the data like within 3 SD of the mean
• What is the formula for chebyshev's theorem?

  (1-1/k^2)
• what is used to compare two data sets with different scale and units?

  coefficient of variation (CV)
• what is used to find the # of SD that a given data value is above or below the mean?

  Z score
• What kind of data do Z scores work best for?

  symmetrical
• what is the equation to fond the percentile given the data value?

  percentile= (# of values less than x) + 0.5/ (number of values in the data set) x 100