Descriptive Statistics

• What is the term for the data collected in psychological investigations?

  Raw data
• What do descriptive statistics summarize?

  Features of a quantitative data set
• What are the two main types of descriptive statistics?

  Measures of central tendency and dispersion
• What are the measures of central tendency?

  Mean, median, and mode
• What do measures of dispersion indicate?

  How spread out individual scores are
• What is the mode in a data set?

  The most frequent score
• What does it mean if a data set is bimodal?

  It has two modes
• Why is the mode useful for discrete numbers?

  It is not affected by outliers
• What is a criticism of the mode in small data sets?

  It may have multiple modes or none
• How is the median calculated?

  Order values and find the middle score
• What is a positive aspect of the median?

  Not affected by extreme outliers
• What is a criticism of the median?

  Not all raw scores are used
• How is the mean calculated?

  Add all scores and divide by total
• What is a positive aspect of the mean?

  Uses all raw data in calculation
• What is a criticism of the mean?

  Easily shifted by extreme values
• How is the range calculated?

  Subtract smallest value from largest
• What does a larger standard deviation indicate?

  Scores are more spread out
• What is a positive aspect of the standard deviation?

  Includes all values in calculation
• What is a criticism of the standard deviation?

  Distorted by extreme values
• What is the formula to calculate percentages?

  Part divided by whole times 100
• How do you find 24% of 250 students?

  Multiply 0.24 by 250
• How is percentage change calculated?

  New number minus old number divided by old
• What is the percentage change from 595 to 724 students?

  21.7%
• What is the percentage change from 1,389 to 974 students?

  -29.9%
• What are correlations in descriptive statistics?

  Relationships between two variables
• What does a positive correlation indicate?

  Both variables increase together
• What does a negative correlation indicate?

  One variable increases while the other decreases
• What is the correlation coefficient?

  A numerical value indicating correlation strength