Descriptive Statistics

• What is the definition of measures of central tendency?

  Calculations to find the average of a data set.
• What is the formula to calculate the mean?

  Add up all scores and divide by the total number of scores.
• What is the mode in a data set?


  The most frequently occurring score.
• How is the median defined?

  The middle value once data is sorted.
• How does the mean differ from the mode and median regarding anomalies?

  The mean is skewed by anomalies, but the mode and median are not.
• What data does the mean utilize compared to mode and median?

  The mean uses all data in a set, but mode and median do not.
• What is the purpose of measures of dispersion?

  Calculations to find the spread/variance/distributions of data.
• What is the formula for calculating the range?

  Highest score minus lowest score.
• What does standard deviation measure?

  How far scores are from the mean.
• Why is the range considered easier to perform than standard deviation?

  Because it involves a simple subtraction of the highest and lowest scores.
• How is the range affected by anomalies?

  The range is skewed if high/low values are anomalies.
• How does standard deviation behave in relation to inaccurate means?

  Standard deviation is robust but skewed by inaccurate means.
• How do you calculate a percentage?

  Number of participants who improved on a test multiplied by 100, divided by the total number of participants.
• What is the formula for calculating percentage increase?

  The increase between the two numbers being compared divided by the original figure, multiplied by 100.
• How do you calculate a percentage decrease?

  The decrease between the two numbers being compared divided by the original figure, multiplied by 100.
• What types of graphs are used to present different types of data?

  • Scattergraph: presents correlational data
  • Bar chart: presents discrete data
  • Histogram: presents continuous data
• What does normal distribution indicate about scores?

  • Most scores are close to the mean
  • Mean, mode, and median are similar
• What characterizes a positive skew in data distribution?

  • Mode and median are lower than the mean
• What characterizes a negative skew in data distribution?

  • Mode and median are higher than the mean