STATS [Quiz 3] - Variability, outliers, and effect size

Which of the measures of dispersion is most impacted by the presence of outliers?

a. standard deviation

b. variance

c. interquartile range

d. range

Range

The summation of (X-mean) for any distribution will equal…

a. the mean of the distribution

b. the standard deviation of the distribution

c. 1

d. 0

0

I measure the entire population at the University. For standard deviation, I should use…

a. sigma

b. s-hat

c. S

d. S-squared

a. sigma

The standard deviation that estimates a population standard deviation from calculations on a sample is…

a. sigma

b. s-hat

c. s

d. s-squared

s-hat

Suppose a professor said that students scoring 1.5 standard deviations above the mean on an exam would get an A.  In the distribution of exam scores the mean was 75 and standard deviation is 6.  Where would a student need to score in order to earn an A?

a. 90 or above

b. 84 or above

c. 81 or above

d. 75 or above

84 or above

When the standard deviation is squared, you get…

a. a number that is twice as big

b. the variance

c. both of the above

d. none of the above

the variance

Which of the following is false?

a. s-hat is used to estimate sigma

b. s-hat uses N-1 as a denominator

c. s-hat will be smaller than sigma when calculated on the same data

d. s-hat is based on a sample

s-hat will be smaller than sigma when calculated on the same data

When standard deviation is small, relative to the unit of measurement, a good interpretation would be…

a. that the distribution is tightly clustered around the mean

b. that the distribution is completely random

c. that there is an extreme skew present

d. none of the above

that the distribution is tightly clustered around the mean

The interquartile range tells you the scores that were made by ____ percent of the distribution.

a. 25

b. 50

c. 75

d. 30

50

A negative number is possible when you calculate the…

a. standard deviation

b. range

c. variance

d. deviation score

deviation score

I take a non-random sample from a population of individuals receiving out-patient treatment.  To calculate standard deviation, I should use…

a. s-hat

b. sigma

c. s

d. s-squared

s

From an effect size estimate of 0.70, you can determine that the means of the two groups are…

a. identical

b. different by 70%

c. related to each other

d. very different

very different

To find an outlier at the bottom of the distribution, I need to know…

a. the mean

b. the 25th percentile

c. the 75th percentile

d. the upper limit outlier

the 25th percentile

Outlier scores of a distribution can be conveyed in a boxplot with a symbol…

a. in the box

b. below the box

c. beyond the whiskers

d. all of these

beyond the whiskers

Which of the following is an empirical distribution?

a. the given names and their frequencies of all high school graduates in the United States for the year 2010

b. the scores obtained from an infinite number of throws of one die

c. the normal distribution contained in Table C in your text

d. all of the above

all above the above?

To calculate values of outliers, you must know the…

a. median

b. mode

c. range

d. IQR

IQR

In a situation where two groups' boxplots are placed on the same scale, side by side, which of the following would be indicative of a small effect size index?

a. The IQR for each group is in almost identical locations

b. The median for the first group will be right about at the 25th percentile of the second group

c. The means for both groups will fall amongst the outliers

d. The means for both groups will be dramatically different

The IQR for each group is in almost identical locations

A z scores of 2.5 indicates a raw score

a. close to the mean

b. that is much smaller than the mean

c. that is much larger than the mean

d. that is 2.5 time larger than the mean

that is much larger than the mean

The effect size estimate, d, is useful because it…

a. provides information about the relationship between two groups

b. shows the effect the independent variable has on the dependent variable

c. allows direct comparisons to other studies

d. all of the above

all of the above

Suppose that should k occur, it will be called a success. If j should occur, it will be called a failure. The ratio of k/(k+j) is…

a. the empirical probability of k

b. the empirical probability of j

c. the theoretical probability of k

d. the theoretical probability of j

the theoretical probability of k

Which of the following is an outlier of a distribution with a 25th percentile of 5 and a 75th percentile of 10?

a. -2

b. 15

c. 18

d. both 15 and 18

18

For distributions that are not normal distributions…

the z-score chart can’t be used

you can eliminate uncertainty about a population if you…

obtain data from all members in the population.