Topics 2-3: Descriptive statistics

Which of the following is a measure of data centrality?

• Median

• Z-score

• Percentile

• Standard deviation

Which of the following is a measure of data variability?

• Mode

• Quartile

• Z-score

• Range

Which of the following measures is NOT easily influenced by outliers in a data set?

• Mean

• Interquartile range

• Variance

• Correlation coefficient

Please find the median of the following data set:

1, 2, 3, 4, 5, 6, 7, 8

• 4

• 5

• 4.5

• 5.5

Which of the following statement is NOT true?

• Median = Q2

• 50th percentile = Q2

• IQR = Q1 - Q3

• Range = Largest - Smallest

When a set of data is skewed to the right, we can say that ___.

• the data set is postively skewed

• the data set is negatively skewed

• the mean is less than the median in most cases

• the median and the mean are almost equal

Which of the following might be a proper estimate of the skewness of the data in the plot?

• 0

• -0.5

• 0.8

• 0.2

What do we know about the a normally distributed population?

• Approximately 68% of the data values fall within one standard deviation of the mean.

• Approximately 95% of the data values fall within one standard deviation of the mean.

• Approximately all of the data values fall within two standard deviations of the mean.

• Approximately 95% of the data values fall within three standard deviations of the mean.

Suppose the mean value of people's IQ is 100 and the standard deviation is 10, what is the z-score of an individual whose IQ score is 120?

• -1

• -2

• 1

• 2

When using the rule of 1.5*IQR to detect outliers of a data set, what is the upper limit?

• Q1 + 1.5*IQR

• Q1 - 1.5*IQR

• Q3 + 1.5*IQR

• Q3 - I.5*IQR