Chapter 2

• 2.1 Frequency tables, grouped frequency tables, histograms, and frequency polygons
• 2.2 A frequency is a count of how many times a score appears. A grouped frequency is a count for a defined interval, or group, of scores.
• 2.3
  • a.

    INTERVAL	FREQUENCY
    100–104	4
    95–99	14
    90–94	6
    85–89	4
    80–84	2
    75–79	6
    70–74	6
    65–69	3
    60–64	5

  • b.
    
  • c.
    
• 2.4
  • a. We can now get a sense of the overall pattern of the data.
  • b. Schools in different academic systems may place different emphasis on faculty conducting independent research and getting published, as well as have varying ranges of funding or financial resources to assist faculty research and publication.
• 2.5 A normal distribution is a specific distribution that is symmetric around a center high point: It looks like a bell. A skewed distribution is asymmetric or lopsided to the left or to the right, with a long tail of data to one side.
• 2.6 Negative; positive
• 2.7 This distribution is negatively skewed due to the data trailing off to the left and the bulk of the data clustering together on the right.
• 2.8
  • a. Early-onset Alzheimer’s disease would create negative skew in the distribution for age of onset.
  • b. Because all humans eventually die, there is a sort of ceiling effect.
• 2.9 Being aware of these exceptional early-onset cases allows medical practitioners to be open to such surprising diagnoses. In addition, exceptional cases like these often give us great insight into the underlying mechanisms of disease.