Sec 3 SMTP Research Sec 3 SMTP Research ModuleModule

ADVANCED STATISTICSADVANCED STATISTICS

Sec 3 SMTP Research Sec 3 SMTP Research ModuleModule

ADVANCED STATISTICSADVANCED STATISTICS

Mrs Goh Cheng WaiMrs Goh Cheng Wai

Relation of data

• A correlation tells us whether two variables vary together

• Correlation coefficient[X: independent variable, Y: dependent variable]

+1 (perfect correlation) X , Y - 1 (perfect negative correlation) X , Y 0 (no correlation between X and Y)

Correlation Cause and effect

• Correlations can only be used to estimate the relationship between two characteristics.

• Do not use them to establish cause and effect.

• E.g. A high correlation between intelligence and exposure to classical music

DOES NOT MEANlistening to classical music causes

one to become intelligent.

ANOVA (Analysis of variance)

• How many sets of data can each t-test compare?

• What if you must compare the means of 3 or more groups?

• ANOVA tells you whether there is an overall difference among the groups.

• However, ANOVA cannot identify where the difference lies or which pair is responsible for the difference.

Standard deviation & standard error

Standard deviation (SD) tells you how scattered the measurements are.

Standard error of the mean (SE) indicates the uncertainty around the estimate of the mean.

Link between error bars and statistical significance

Standard error bars do not overlap.Difference may be significant or insignificant.

Standard error bars overlap. Difference is insignificant (p 0.05)

Hands-on session

3S1 and 3P3 (first seven in the list): Comp Lab 1

3S2 and 3O3: Comp Lab 2

3A3: Comp Lab 3

3I3 + 3P3 (next seven in the list): Comp Lab 4

Deadline to submit 1st draft of proposal to mentor: Monday 11 April