Exam 3: Measures of Variability

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. -Calculate the median.

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. -Calculate the range.

The fifth decile coincides with the

A group of inmates at a State House of Correction were tested during orientation on the LSI (Level of Security Inventory) to assess their possible security risk while incarcerated. Their scores were as follows: 4,8,2,4,6,5,7,3,4,6,5,7,4,5,4,3,7,6,5,5. -Find the median

For the following, use SPSS: A forensic psychologist was hired to test a group of police recruits and weed out those who might have any anti-social tendencies. The psychologist chose to test them on the MMPI2 and use their scores on the ASP Scale (Anti Social Practices) to identify any possible problems among the group. Their scores were as follows: 50,53,53,47,48,55,44,46,47,45,68,43,50,51. -Find the median

When new scores that are close to the mean are added to any distribution, there is a fairly high probability that the range will

Of the following, the measure(s) of variability is (are),

A distribution with a large standard deviation must also have a large

The third quartile begins between the

The standard deviation demands that the data form be at least

When a student takes a 600-item standardized test and is told he/she is at the 70th percentile, it means that the student

If you were to receive a score on an exam which placed you at the 90th percentile, then 90% of those taking the test scored below you.

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 mean, range and standard deviation: 12, 2, 5, 9, 11, 10, 10, 4.

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 standard deviation for the group.

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 range for the group.

The concept of "individual differences" may best be described by

If the range on a mesokurtic distribution is equal to 60, then the standard deviation will be approximately equal to

The interquartile range includes only the middle-most 25% of the distribution.

If a student takes a test and gets 70% of the items right, then the student's score is at the 70th percentile.

A leptokurtic distribution has a relatively small standard deviation.