Practice Quiz Chapter 04

. Six young people report their wage rate to a researcher: $9, $11.50, $12, $14.50, $15, and $16 per hour, respectively. What is the average wage rate?

a) $12.50/hour

b) $13/hour

c) $23/hour

d) $3/hour

e) $33/hour

. The sigma (?) symbol means the researcher must do what?

a) Ignore the variable's level of measurement

b) Calculations following the symbol should be completed for each case the results summed

c) The total number of cases should be signified together

d) The standard deviation is calculated next

e) The standard deviation should be used and not the mean

. If a student makes a total of $33,072 in salary a year, how much do they make on average each week?

a) $363

b) $366

c) $636

d) $633

e) $333

. If a student makes a yearly salary of $27,615, what is their average weekly income?

a) $531

b) $513

c) $315

d) $355

e) $555

. Which of the following is not a necessary step to calculate a ratio-level variable's standard deviation?

a) Calculate the variable's average or mean

b) Subtract the mean from the value of each case

c) Square the deviations from the mean

d) Calculate the variable's range

e) Calculate the square root of the variance

. If a case has a z-score of -1, then you can say the following about that case:

a) The mean of the case is one standard deviation from the range

b) The case must be multiplied by another -1 for further calculations

c) The mean for the case is negative

d) The standard deviation for the case is -1

e) It has a value that is one standard deviation below the average value of the variable

. If a young worker makes $15.60/hour and the average wage rate for their age group is $12.56 with a standard deviation of 3.04 then what is the z-score for that worker?

a) 3

b) 2

c) 0

d) 10

e) 1

. If another young worker makes $20.02/hour and the average wage rate for their age group is $16.84 with a standard deviation of 6.36 then what is the z-score for that worker?

a) 1.5

b) 0.5

c) 0.05

d) 5

e) 0.65

. Cases that stand out as different due to their unusually high or low values are known as what?

a) Outliers

b) Averages

c) Extreme attributes

d) Z-scores

e) A sigma

. What don't you do if you notice outliers in your data?

a) Double-check to make sure the outliers don't represent missing data or data-entry errors

b) Potentially exclude them from analysis

c) Re-adjust their values so they are more in line with the rest of the cases in the dataset

d) Include them but explain how they affect the statistics presented

e) Present your results with and without outliers

. What is the normal distribution also known as?

a) An outlier

b) The standard deviation

c) A bin interval

d) A bell curve

e) Maximum vale

. Which of the following is not a characteristic of the normal distribution?

a) It is symmetrical

b) The mean, median and mode of the distribution are all the same

c) The distribution only has one mode

d) The distribution is multi-modal

e) The mean, the median and the mode fall on the exact middle of the distribution

. Which of the following is not true about the area underneath the curve of a normal distribution?

a) The curve is centred on 0.

b) 68% of the area beneath the curve is between -1 and 1 standard deviations from the mean

c) 95% of the area beneath the curve is between -2 and 2 standard deviations from the mean

d) 99% of the area beneath the curve is between -3 and 3 standard deviations from the mean

e) 60% of the area beneath the curve is between -1 and 1 standard deviations from the mean

. Assuming a normally distributed variable, calculate the value of +1 standard deviation from the mean for a variable's distribution with an average wage rate of $13/hour and a standard deviation of $2.40?

a) $15.40

b) $14.50

c) $1.40

d) $5.40

e) $4.50

. Assuming a normally distributed variable about youth wage rates, with an average rate of $13/hour and a standard deviation of $2.40, we know that 68% of young people will earn between what and what per hour?

a) $16.10 and $18.40 per hour

b) $10.60 and $15.40 per hour

c) $12.60 and $16.40 per hour

d) $16.20 and $19.40 per hour

e) $16.60 and $19.40 per hour

. Assuming a normally distributed variable about youth wage rates, with an average rate of $13/hour and a standard deviation of $2.40, we know that 95% of young people will earn between what and what per hour?

a) $2.80 and $17.80 per hour

b) $12.20 and $17.80 per hour

c) $8.20 and $17.80 per hour

d) $17.20 and $18.80 per hour

e) $18.20 and $20.80 per hour

. Assuming a normally distributed variable about youth wage rates, with an average rate of $13/hour and a standard deviation of $2.40, calculate the percentage of students who earn less than $15/hour using an 'area under the normal curve' calculator.

a) 0.83

b) 0.80

c) 0.08

d) 0.083

e) 0.38

. What statistics do researchers use to describe the shape of non-normal distributions?

a) Median and mode

b) Mean and standard deviation

c) Range and interquartile range

d) Ebb and flow

e) Skew and kurtosis

. What does the skew of a distribution indicate?

a) How asymmetrical a variable's distribution is

b) How symmetrical a variable's distribution is

c) The centre of a normal distribution

d) Where the tails of a normal distribution touch the horizontal axis

e) Where the second mode of a normal distribution is

. What does the kurtosis of a distribution measure?

a) Its normality

b) The peak or flatness of the distribution's centre

c) Its standard deviation

d) Its mean

e) Its centre

. The most common way to describe the centre of a ratio-level variable's distribution is the standard deviation.

a) True

b) False

. The mean is a theoretical construct and not linked to a specific case.

a) True

b) False

. The statistic that is most often used to describe the dispersion of a variable at the ratio level of measurement is the standard deviation.

a) True

b) False

. The variance is the square of the mean.

a) True

b) False

. The standard deviation has the same unit of measurement as the variable.

a) True

b) False

. A variable's standard deviation is a measure of how far cases are spread out around the mean of a variable.

a) True

b) False

. If a variable's standard deviation is larger than its mean then we know the variable is not widely dispersed.

a) True

b) False

. The formula for the variance is identical to the formula for the standard deviation, except you do not take the square root of the result.

a) True

b) False

. Z-scores are used primarily to compare the relative positions of two or more cases that are part of different distributions.

a) True

b) False

. In terms of calculating the z-score for a case, the S in the formula represents the standard deviation for the variable in question.

a) True

b) False

. Because of the way they are calculated, the mean, standard deviation and variance are not susceptible to the effect of outliers.

a) True

b) False

. The median is less affected by outliers than the mean, standard deviation and variance.

a) True

b) False

. The way outliers affect the mean, standard deviation and variance highlights the importance of looking at how a variable is distributed before performing statistical analysis on it.

a) True

b) False

. Histograms are used to display continuous variables.

a) True

b) False

. The width of each bar in a histogram captures an equal-sized interval of values.

a) True

b) False

. Each bar on a histogram is called an outlier.

a) True

b) False

. A normal distribution is a tool used to describe the shape of a distribution.

a) True

b) False

. The mean and standard deviation are not relevant to the normal distribution.

a) True

b) False

. Z-scores and the normal distribution can also be used to determine the percentage of cases that are above or below a specific value of a variable.

a) True

b) False

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