Unit 6.1: Statistical Analysis

Question 1

What are error bars?

Answer 1

Graphical representation of data variability

Question 2

What do error bars represent?

Answer 2

• The mean, and how variable data is with regards to the mean
• Besides mean, can depict range/standard/deviation/error deviation/other estimates of variability

Question 3

What is the mos useful thing error bars represent? How can they be interpreted?

Answer 3

• Standard Deviation
• When estimate of variability widespread -> mean unreliable/highly variable
• When estimate of variability narrowly spread -> mean more reliable

Question 4

What happens if we assume a test has normal distribution? How is it depicted?

Answer 4

• 68% of data lies between +- 1 Standard Deviations of the mean
• 95% of data lies between +- 2 Standard Deviations of the mean
• Depicted by Gaussian function (Campana de Gauss)

Question 5

How is Standard Deviation useful for comparing means and spread of data between two or more samples?

Answer 5

• More standard deviation -> wider variation / less standard deviation -> narrower variation
• Overlapping of data = suggests data do not have significant differences

Question 6

What can Standard Deviation not be used as?

Answer 6

• As an inferential Statistic
• Cannot make predictions solely based on Standard Deviation (use suggests…)

Question 7

What it as t-test? How can we interpret its results?

Answer 7

• Method to determine if there is a difference between the means of two populations
• Test will give a p-value = probability of no difference existing between two values
• H0 = no significant difference between two samples
• H1= There is a significance difference
• If P-Value > SL -> Accept H0, If P-Value </= SL -> Reject H0
• If T-Value < CV -> Accept H0, If T-Value > CV -> Rehect H0

Question 8

What can correlation not be used as proof of?

Answer 8

Proof of cause