E370 Ch 2

How do we find the median if the number of observations in a data set is odd? - By averaging the minimum and maximum values - By averaging the first and the third quartiles - By taking the middle value in the sorted data set after eliminating outliers - By taking the middle value in the sorted data set

By taking the middle value in the sorted data set

Which of the following is the most influenced by outliers? - 75th percentile - 1st quartile - Median - Mean

Mean

When outliers are present in the data set, which measure is the best to describe central tendency in the data? - standard deviation - median - mean - weighted mean

Median

Which measure would you use to describe central tendency for qualitative data? - mean - median - mode - weighted mean

Mode (the value that appears most frequently in a data set)

If two groups of numbers have the same mean, then - their modes must also be equal - their medians must also be equal - their standard deviations must also be equal -None of the suggested alternatives is correct

None of the suggested alternatives is correct

Which of the following symbols represents the standard deviation of the population? x̄ σ σ^2 μ

σ

The Boom company has recently decided to raise the salaries of allemployees by 10%. Which of the following is(are) expected to be affected by this raise? - Mean and mode only - Mean, median, and mode - Mode and median only - Mean and median only

- Mean, median, and mode

The mean of the sample - can never be zero - is always smaller than the mean of the population from which the sample was taken - can never be negative - None of the suggested alternatives is correct

- None of the suggested alternatives is correct

Which one of the following statements is true for a right-skewed distribution? - The mean is greater than the median. - The mean is less than the median. - The mean is greater than the mode. - The mean is roughly equal to the median.

- The mean is greater than the median.

The standard deviation of a sample of 100 elements taken from a very large population is determined to be 60. The variance of the population - cannot be larger than 60 - can be any value greater than zero - must be at least 100 - cannot be larger than 3600

- can be any value greater than zero

Comparing the consistency (variability) between two data sets when their means are very different is best done with the - median - standard deviation - coefficient of variation - z-score

- coefficient of variation

Since the population is always larger than the sample, the value of the sample mean - is always smaller than the true value of the population mean - could be larger, equal to, or smaller than the true value of the population mean - is always larger than the true value of the population mean - is always equal to the true value of the population mean

- could be larger, equal to, or smaller than the true value of the population mean

During a cold winter, the temperature stayed below zero for ten days (ranging from -20 to -5). The variance of the temperatures of the ten-day period - cannot be computed since all the numbers are negative - must be positive - is negative since all the numbers are negative - can be either negative or positive

- must be positive (Variance can't be neg)

μ is an example of a - mode - sample statistic - population parameter - population variance

- population parameter

If the variance of a data set is correctly computed with the formula using n - 1 in the denominator, which of the following is true? - the data set could be either a sample or a population - the data set is a sample - the data set includes all subjects of interest in the study - the data set is a population

- the data set is a sample

Which of the following statements is NOT true concerning the attributes of z-scores? - z-scores are equal to zero for data values equal to the mean of the distribution - z-scores can be positive or negative for data values above the mean of the distribution - z-scores are negative for data values below the mean of the distribution - z-scores are positive for data values above the mean of the distribution

- z-scores can be positive or negative for data values above the mean of the distribution

In 2009, the average donation to the Help Way was $225 with a standard deviation of $45. In 2010, the average donation was $400 with a standard deviation of $60. In which year did the donations show a more dispersed distribution? Hint: to answer this question, you need to calculate the coefficient of variation for each year. The donations show a more dispersed distribution in ["2009", "2010"] because the coefficient of variation is ["smaller", "larger"] for that year.

2009, Larger

Using the sample data, it was computed that the z-score for a data value of $166 is 0.96. Calculated z-score is best interpreted as:

Spending of $166 is 0.96 standard deviations above the mean spending

Is it possible for a data set to have more than one mode? - No, there must always be a single mode, or else there is no mode. - Yes, if two or more values in a data set occur the same number of times. - Yes, if there are at least two different values in a data set, there is always more than one mode. - Yes, if two or more values in a data set occur with the most frequency.

Yes, if two or more values in a data set occur with the most frequency.

The median is defined as the - middle point in a data set - most frequent value of a data set - average of a data set - closest value to the mean

- middle point in a data set

Which of the following symbols represents the mean of the sample? x̄ σ n μ

x̄