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Answers to the checkpoints of chapter 2

Checkpoint 1

  • Qualitative, a few categories, you can’t use it to make calculations.
  • Dichotomous.
  • Nominal, ordinal, interval and ratio.
  • The following:
  1. nominal
  2. interval
  3. ratio
  4. ordinal
  5. ratio
  6. ratio
  7. ordinal
  8. ordinal
  9. ratio
  10. ordinal.


Checkpoint 2

  • A number that expresses the number of observations relative to the total number of observations.
  • The total percentage is 25%, the applicable percentage is 50%.


Checkpoint 3

  • The objective and the measurement level
  • If the trend is ascending and you want to compare categories.
  •  The following: 

  • a.    bar chart or pie chart;

b.    histogram;

c.    dot plot or line graph;

d.    box plot;

e.    bar chart;

f.     histogram (or a bar chart) if you want to see it by “size,” otherwise a box plot if you just want to show the distribution.


Checkpoint 4

  • Mode, median and mean.
  • Median.
  • income in dollars: mean, median or mode
    income in categories: median or mode
    professional group: mode
    job level: median or mode
    number of years in the job: mean, median or mode


Checkpoint 5

  • Interquartile range for ordinal variables and for continuous variables with a skewed distribution; variance for continuous variables with a minimum interval measurement level (preferably with a symmetrical distribution).
  • If you’re working with sample data (and not population data).
  • The problem with quadratic measures is that they are difficult to interpret. After all, we are interpreting the square of a measure. What does that mean exactly?


Checkpoint 6

  • At 1-sigma 68.27% of the observations fall within +1 and -1 of the standard deviation from the center; at 2-sigma = 95.44% and 3-sigma = 99.73%.
  • 100 +/- 4 * 15, so 100 +/- 60. According to the Chebyshev’s rule, at least 94% of all IQs are between 40 and 160.
  •  If your IQ falls in the 94th percentile, it means that 94% of the distribution have an IQ that is the same as or a lower than yours, and (only) 6% have an IQ that is higher than yours. In that case, you are considered to be very intelligent.
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