Measuring Central Tendency and Variability

What is the meaning of central tendency?

 

What are the most popular measures of central tend?

 

When is the median the best measure of central tendency over mean?

 

  • For which level of measurement (Nominal, Ordinal, Interval, Ratio), the central tendency is only    measured by mode (mean & median do not work!)?

What does standard deviation and range represent? Explain the meaning of these terms?