Ch 2

What is the median for the following amounts: $9.75, $11.75, $12.00, $8.75, $9.50, $8.50, $8.75?

9.50

The three measures of central tendency--the mean, median, and mode--are all interchangeable.

False

Which measure of central tendency is based on all the scores in the distribution?

Mean

Which measure of central tendency should you use when your level of measurement is interval?

Mean

Which measure of central tendency should you use when your level of measurement is ordinal?

Median

Which measure of central tendency should you use when your level of measurement is nominal?

Mode

interval level of measurement

a test or an assessment tool is based on some underlying continuum such that we can talk about how much more a higher performance is than a lesser one. A distinguishing characteristic of interval-level scales is that the intervals or spaces or points along the scale are equal to one another. Ten words correct is 2 more than 8 correct, and 6 is 2 more than 4 correct.

measures of central tendency

come in three flavors: the mean, the median, and the mode

nominal level of measurement

defined by the characteristics of an outcome that fit into one and only one class or category. nominal level is the least precise level of measurement.

ratio level of measurement

is characterized by the presence of an absolute zero on the scale. What that zero means is the absence of any of the trait that is being measured.

average

is the one value that best represents an entire group of scores. big group of data can be summarized using an average. It's the point in a range of values that seems to most fairly represent all the values.

When there are a few extreme scores that skew the data, such as US household income, the ___________ would be the most appropriate measure of central tendency.

median

What is the formula for computing the mean?

ΣX / n

Median

defined as the midpoint in a set of scores. It's the point at which one half, or 50%, of the scores fall above and one half, or 50%, fall below. List the values in order, from either highest to lowest or lowest to highest. Find the middle-most score. That's the median. An even number of scores means there is no middle value. When there is an even number of values, the median is simply the mean of the two middle values. If two middle-most values are the same then the median is same as both of those middle-most values. When you have a set of scores in which one or more scores are extreme, the median better represents the centermost value of that set of scores than any other measure of central tendency.

Mode

is the value that occurs most frequently. Like the median, there is no formula for computing the mode. List all the values in a distribution but list each value only once. Tally the number of times that each value occurs. The value that occurs most often is the mode.

The measure of central tendency considered the most precise is ______.

mean

If your current examination mean is 97.2 and you receive a 99 on the next examination, what effect will this have?

mean will increase

mean (M)

most common type of average that is computed. The mean is simply the sum of all the values in a group, divided by the number of values in that group. represented by the letter M and is also called the typical, average, or most central score and referred to as arithmetic mean

scale of measurement

scale or level dictates the specific measure of central tendency you will use. nominal, ordinal, interval, and ratio.

ordinal level of measurement

stands for order, and the characteristic of things being measured here is that they are ordered. (ranking)

What is another term for the mean in a set of data?

the arithmetic average

What does the symbol Σ represent?

the sum of scores