Quiz Over Chapter 2 of the 6th Edition

Descriptive Statistics

Picture Techniques for Summarizing Data

  1. If you add all the numbers in the "f" column of an ungrouped frequency distribution, you'll get ___ .
  2. In Excerpt 2.1, how many students exercised vigorously less than 3 days a week?
  3. How would you interpret this if it were presented in a stem-and-leaf display: 6|1129
  4. What determines the height of each "bar" in a histogram?
    1. N
    2. f
    3. M
    4. r
    5. R
  5. The technical names for the horizontal and vertical axes in a bar graph or line graph are ____ and ____ , respectively.
  6. "Frequency polygon" is to "line graph" as "_____" is to "bargraph."
  7. When raw scores are summarized via a grouped frequency distribution, is there "loss of information?"  What about when raw scores are summarized via a stem-and-leaf display?
  8. In Excerpts 2.4 and 2.5, each vertical bar reveals information about a portion of the collected data by means of the vertical bar's _______ (width/height).

Distributional Shape
  1. A normal distribution is often said to be "___-shaped."
  2. (T/F) In Excerpt 2.6, the distribution of ages would have resembled more closely a normal distribution if 24% of the group had been between the ages of 21-25, with only 8% of the group between the ages of 26-30.
  3. What kind of skewness is associated with the data shown in Excerpt 2.1?
  4. Based on the information displayed in Excerpt 2.7, the "extreme" scores were _____ (high/low).
  5. What does a leptokurtic distribution look like?  A platykurtic distribution?
  6. What are the numerical values for skewness & kurtosis for a symmetrical mesokurtic distribution?

Measures of Central Tendency
  1. (T/F) In the field of statistics, the term "average" is used to signify only the mean.
  2. Which measure of central tendency gives the "middle score" (or "mid-point")?
  3. What's the median & mean for: 14, 4, 10, 8, 6, 12, 16?  Change 16 to 86 and re-answer.
  4. Which measure of central tendency assumes the highest score in skewed distributions?
  5. What Greek letter is sometimes used to signify the mean?
  6. If the mean, median, and mode are 50, 60, and 70, respectively, does that suggest negative skewness?

Measures of Variability
  1. In Excerpt 2.7, if the bars over the scores of 1 and 11 had been reversed, and if the bars over the scores of 1 and 12 had been reversed, there would have been ____ (more/less) variability among the study's patients.
  2. How many quartiles are there?  How are they labeled?  Which one is the highest?
  3. What is the name for the numerical distance between the 75th and 25th percentiles?
  4. For these data, what is the semi interquartile range equal to?      9, 1, 6, 5, 4, 7, 2, 5
  5. (T/F) The semi interquartile range is always equal to one-half the distance between Q1 & Q3.
  6. In Excerpt 2.16, what percentage of the participants were between 28 and 59 years old?
  7. (T/F) Researchers rarely report both the SD and the variance for the same data set.
  8. In Excerpt 2.20, the variance of the third variable (Number of places slept last week) would be equal to ___.
  9. (T/F) If all of the scores are negative, the SD itself will turn out to be a negative value.
  10. One symbol for the variance is s2; another symbol for the variance is ___.
  11. If N = 100 and SD = 10, you should guess that the range of scores = ___ .
  12. If a researcher summarizes his/her data by saying  38 ± 12, what does the 12 indicate?
  13. If a group of scores has a mean equal to 10 and a SD equal to 20, the coefficient of variation will be equal to ___.

Standard Scores
  1. A standard score simply indicates the number of ____ between a raw score and ____.
  2. A z-score of +1.5 is equal to a T-score of  __. A T-score of 48 is equal to a z-score of __.
  3. Look again at Excerpt 2.20, and concentrate on the 3rd variable (Number of places slept last week). If one of the research participants had slept in 5 different places, that participant's z-score would be equal to ___ .

A Few Cautions
  1. (T/F) Researchers sometimes use the term "skewed" to mean something other than "positively skewed" or "negatively skewed."
  2. (T/F) If a researcher uses the term "average" without specifying whether it's the mean, median, or mode, you'll most likely be correct if you guess that it's the median.
  3. A score in a data set that lies far away from the rest of the scores is called a(n)_____.
  4. In Excerpt 2.27, a rule for identifying outliers is articulated. If that rule is applied to the age data in Excerpt 2.19, are there any outliers?

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