Experimental

• What is the purpose of control variables ?

  To ensure experiment is valid
• What is the issue with systematic errors ?

  affect reproducibility
• What does it mean is an experiment is repeatable ?

  repeated by the same person, same equipment and achieve the same results
• What reduces accuracy ?

  systematic and random errors
• accuracy = when a result is close to the true value
• precision = repeated results are clustered together
• What can repeating the experimennt help determine ?

  the precision of results
• reproducibility = the ability for a different person to repeat the experiment and get same results
• What is the purpose of the student t-test ?

  To find if the difference between means is significant
• When would you use a paired t-test ?

  When the sets of data are coming form the same individual.
• When would you use an unpaired t-test?

  When the sets of data come from different individuals
• What is the degree of freedom for a paired t-test ?

  n-1
• What is the degree of freedom for an un-paired t-test ?

  (n1+n2)-2
• In a students t-test if the value of t is greater than or equal to the critical value then the difference is significant so you can reject H0.
• What do overlapping error bars indicate when comparing data?

  there is no significant difference
• What is the purpose of simpsons index ?

  To measure species diversity, considering both species richness and evenness.
• In simpsons index what does the n and N represent ?


  n is the total number of organisms in one species

  N is the total number of all organisms
• How do you interpret simpsons index?

  The closer to 1 your value, the more diverse the habitat.
• What is the purpose of spearmans rank ?

  Ranks data in order of size, indicating the strength and direction of correlation.
• What does each r value represent in spearman's rank ?

  r = -1 : negative correlation

  r = 0 : no correlation

  r= 1 : positive correlation
• In spearmans rank if your value is greater than the c.v the correlation is significant and you can reject the null hypothesis.
• When discussing reliability of experiment what could be considered ?

  sample size