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 avoids issues with 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
• Why might a CEO choose to state the mean salary?

  To present the company in a favorable light
• What does the range measure?

  The spread between the smallest and largest values
• How is the range calculated?

  Subtract the smallest value from the largest
• What is a positive aspect of the range?

  It is easy to calculate
• What is a criticism of the range?

  Extreme scores can distort its value
• What does the standard deviation indicate?

  How spread out scores are around the mean
• What is a positive aspect of the standard deviation?

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

  It is distorted by extreme values
• What is the formula to calculate a percentage?

  Part divided by whole times 100
• What is the first step in calculating a percentage of a number?

  Convert the percentage to a decimal
• How do you calculate the percentage of 595 out of 2480?

  Divide 595 by 2480 and multiply by 100
• What does a percentage change indicate?

  The difference between two numbers as a percentage
• How do you calculate the percentage change from 595 to 724?

  Subtract, divide by old number, then multiply by 100
• What are correlations in descriptive statistics?

  Relationships between two variables
• What are the types of correlations?

  Positive, negative, and zero correlations
• What are the strengths and weaknesses of the mean, median, and mode?

  Mean:

  • Strength: Uses all data points
  • Weakness: Sensitive to extreme values

  
  

  Median:

  • Strength: Not affected by outliers
  • Weakness: Not all scores used

  
  

  Mode:

  • Strength: Useful for discrete numbers
  • Weakness: May have multiple modes or none
• What are the strengths and weaknesses of the range and standard deviation?

  Range:

  • Strength: Easy to calculate
  • Weakness: Distorted by extreme values

  
  

  Standard Deviation:

  • Strength: Includes all values
  • Weakness: More complex to calculate
• What are the steps to calculate percentages?

  1. Convert percentage to decimal
  2. Multiply by the total number
  3. For percentage change:

  • Subtract old from new
  • Divide by old
  • Multiply by 100
• What are the types of correlations and their meanings?

  • Positive Correlation: Both variables increase together
  • Negative Correlation: One variable increases while the other decreases
  • Zero Correlation: No relationship between variables