Standard Deviation

• What does the SD tell you?


  How much the values in a single sample vary
• What is SD a measure of?

  The spread of values about the mean
• What does a large SD mean?

  the values in the sample vary a lot
• what does a small sd mean?

  most of the sample data is around the mean, so varies little
• differing SD from google

  
• What can standard deviations be plotted on?

  A graph or chart of mean values using ERROR BARS
• What do error bars do?


  extend one SD above and one SD below the mean (so the total length of error bar is twice the SD)
• a longer error bar =?

  Larger SD and the more spread out sample data is from the mean
• Where is the mean?

  IN the middle of the error bar