Chapter 11

measure of center

A measure of central tendency (measure of center) is a value that attempts to describe a set of data by identifying the central position of the data set (as representative of a "typical" value in the set). We are familiar with measures of central tendency called the mean, median and mode.

satatistical question

A statistical question is one that can be answered by collecting data and where there will be variability in that data. This is different from a question that anticipates a deterministic answer. For example, "How many minutes do 6th grade students typically spend on homework each week?" is a statistical question.

mean absolute deviation

Explain. You have used the interquartile range which describes the variability of a set of data. Another way to describe the variability of a set of data is to use its mean absolute deviation. The mean absolute deviation of a set of data is the average distance between each data value and the mean.

third quatile

For a set of data, a number for which 75% of the data is less than that number. The third quartile is the same as the median of the part of the data which is greater than the median. Same as 75th percentile. See also.

measures of variation

Measures of variation are either properties of a probability distribution or sample estimates of them. The range of a sample is the difference between the largest and smallest value. The interquartile range is potentially more useful.

mode

Number used the most

outliers

Outlier. more ... A value that "lies outside" (is much smaller or larger than) most of the other values in a set of data. For example in the scores 25,29,3,32,85,33,27,28 both 3 and 85 are "outliers".

mean

The average

range

The difference between the lowest and highest values. In {4, 6, 9, 3, 7} the lowest value is 3, and the highest is 9, so the range is 9 − 3 = 6. Range can also mean all the output values of a function. See: Range of a function. The Range (Statistics)

first quartile

The first quartile is defined as the middle number between the smallest number and the median of the data set. The second quartile is the median of the data. The third quartile is the middle value between the median and the highest value of the data set.

interquartile range

The interquartile range (IQR) is a measure of variability, based on dividing a data set into quartiles. Quartiles divide a rank-ordered data set into four equal parts.

median

The middle in the data

average

a number expressing the central or typical value in a set of data, in particular the mode, median, or (most commonly) the mean, which is calculated by dividing the sum of the values in the set by their number.

quartiles

each of four equal groups into which a population can be divided according to the distribution of values of a particular variable.