Exam 3: Measures of Variability

Of two golfers, each of whom drives the ball the same average distance, the one with the smaller standard deviation would be

The smallest possible standard deviation is equal to zero.

The more heterogeneous the distribution of scores,

A researcher gives IQ tests to a large group of adults, and discovers that the mean, median and mode all equal 100. The highest score in the group was 130 and the lowest was 70. Between IQ's of 75 and 125, 80% of the group was found, and 50% were found between IQ's of 90 and 110. The shape of the graphed distribution was mesokurtic. -The ninth decile coincided with an IQ of

The Children's Depression Inventory (CDI), developed from Beck's Depression Inventory is a self-report instrument with 27 sets of statements. Higher scores indicate higher levels of depression. Scores above 13 are said to indicate a Major Depressive Disorder (MDD) and few false positives have been reported. A random sample of 20 fifth grade students was selected and given the test. Their scores were as follows: 9,10,11,9,8,9,17,2,7,11,6,12,9,10,9,9,8,10,14,1. -Find the mode for the group.

When the range of a unimodal distribution equals approximately 6 times the standard deviation, then the curve is most likely to be

When a deviation score has a negative value, then

A researcher wished to evaluate the operating life of a certain brand of storage battery. A group of 30, brand-new batteries was selected and placed in 30 identical automobiles. The lights in each automobile were then turned on (without running the engines), and the length of time before the batteries were fully discharged (lights went out) was recorded. The scores, in hours, were: 15, 10, 20, 18, 18, 11, 11, 11, 11, 12, 12, 12, 10, 9, 9, 8, 9, 9, 11, 11, 11, 15, 12, 12, 12, 10, 12, 12, 15, 12. -For the following set of scores, calculate the standard deviation: 5, 10, 10, 5, 5, 2, 3, 5, 9, 7.

A negative standard deviation indicates that most of the scores were below the mean.

A researcher gives IQ tests to a large group of adults, and discovers that the mean, median and mode all equal 100. The highest score in the group was 130 and the lowest was 70. Between IQ's of 75 and 125, 80% of the group was found, and 50% were found between IQ's of 90 and 110. The shape of the graphed distribution was mesokurtic. -The standard deviation was equal to approximately

A researcher wished to evaluate the operating life of a certain brand of storage battery. A group of 30, brand-new batteries was selected and placed in 30 identical automobiles. The lights in each automobile were then turned on (without running the engines), and the length of time before the batteries were fully discharged (lights went out) was recorded. The scores, in hours, were: 15, 10, 20, 18, 18, 11, 11, 11, 11, 12, 12, 12, 10, 9, 9, 8, 9, 9, 11, 11, 11, 15, 12, 12, 12, 10, 12, 12, 15, 12. -For the following set of scores, calculate the standard deviation; 5,8,10,10,12,12,12,14,14,16,19.

If two distributions have the same mean and same range, then they must also

The distribution with the largest standard deviation necessarily has the largest range.

The term which defines the flatness or peakedness of a curve is

Of the following, which can be calculated even though the data are in ordinal form?

The Children's Depression Inventory (CDI), developed from Beck's Depression Inventory is a self-report instrument with 27 sets of statements. Higher scores indicate higher levels of depression. Scores above 13 are said to indicate a Major Depressive Disorder (MDD) and few false positives have been reported. A random sample of 20 fifth grade students was selected and given the test. Their scores were as follows: 9,10,11,9,8,9,17,2,7,11,6,12,9,10,9,9,8,10,14,1. -Is the distribution skewed?

If two football running-backs have the same yards-per-carry average, but player A has a larger standard deviation than player B, then

A researcher gives IQ tests to a large group of adults, and discovers that the mean, median and mode all equal 100. The highest score in the group was 130 and the lowest was 70. Between IQ's of 75 and 125, 80% of the group was found, and 50% were found between IQ's of 90 and 110. The shape of the graphed distribution was mesokurtic. -The first decile coincided with an IQ of

If a student takes a test and gets a raw score which is at a point that is greater than 70% of all students taking the same test then the student's score is at the 70th percentile.

The measure of the entire width of the distribution is called the