bus 230 chappell, chapter 3

If a data set has an even number of observations, the median is calculated in two steps:

(1) put them in order (2) take average of middle 2

The mean of a sample is computed by summing ___________ and then dividing by ___________

values of xi, dividing by n

The descriptive measure of dispersion that is based on the concept of a deviation about the mean is the _________

variance

List the four measures of dispersion

variance, standard deviation, range, IQR (interquartile range)

The sum of deviations of the individual data elements from their mean is always _______

zero

What symbol represents the mean of the population?

μ (mu)

The coefficient of correlation can never be ___________________

can never be > 1, can never be < 1

The median is a measure of _________.

central location

The most important statistical descriptive measure of the location of a data set is the _________

mean

List three measures of central location

mean, median, mode

The value which has half of the observations above it and half the observations below it is called the __________.

median

Since the mode is the most frequently occurring data value, it is always _________ than the mean

mode can be >, <, or equal to the mean

What symbol represents the size of the sample?

n

In computing the mean of a sample, the value of ∑xi is divided by ______

n (sample size)

The variance can never be _________

negative

The variance of the sample can never be _________

negative

The sample variance is always (LARGER/SMALLER/THE SAME AS) the population variance

none of these (can be larger, smaller, and the same as)

What are two numerical measures of the linear association between two variables?

Sxy and rxy

The 75th percentile is referred to as the

3rd quartile

The variance of a sample of 81 observations equals 64. The standard deviation of the sample equals __________

8 (square root of 64)

What symbol represents the size of the population?

N

The symbol σ2 is used to represent __________

population variancec

The interquartile range is _____

q^(3)-q^(1 )

The difference between the largest and the smallest data values is the ___________.

range

The measure of dispersion that is influenced most by extreme values is the _________

range

When the data are skewed to the right, the longer tail of the distribution is on the __________

right

The variance of a sample of 169 observations equals 576. The standard deviation of the sample equals _________.

s= 24 (square root of 576)

Since the population size is always larger than the sample size, then the sample statistic is always __________ compared to the population parameter

sample statistic can be >, <, or = to population parameter