investigating human selection

• complete the equation

  A) s

  B) N

  C) 2

  D) X

  
• what is an error bar

  An error bar is a line through a point on a graph, parallel to

  one of the axes, which represents the variation or spread

  relative to the mean.

  Error bars most often represent the standard deviation of a

  data set relative to the mean.
• what do error bards indicate about statistical significance?

  A "significant result" means that the results that are seen are most likely not due to chance.  

  In any experiment or observation that involves sampling from a population, there is always the possibility that an observed effect would have occurred due to chance alone.  

  But if result is "significant,"  then the investigator may conclude that the observed effect actually reflects the characteristics of the population rather than just sampling error or chance. 
• Standard deviation

  The standard deviation is NOT a statistical test, rather the standard deviation is a measure of variability.  

  To assess statistical significance, the sample size must also be taken into account.  

  Therefore, while standard deviation error bars can give you a clue about statistical significance, you must actually perform a statistical test to draw a valid conclusion.