1. Dr. Carolin Elizabeth George
Test Of Significance
Dr. Carolin Elizabeth George
Test of significance

2. Learning objectives At the end of the session, you will be able to
Know different types of statistical test
Will be able to decide which test to be applied to a given set of data
Will be able to report association
Concept of correlation
Test of significance

3. Eg:weight of the babies
Recap
Number
Character,
Any Number
Eg:weight of the babies
Describing type
Eg: gender
Counts
No. of babies died
Order
Pain scale
Test of significance

4. Look at the RQ
Is tobacco chewing associated with oral cancer? How do I go about it?
How do you design a study?
How do you find the answer?
Test of significance

5. NTP- Null hypothesis, test, pvalue
How do we go about it
1. State null hypothesis
H0= Smoking and lung cancer are not associated
2. Apply a TOS
3. Look at the p value.
If the p is greater than 5%, then accept the null hypothesis
If p is less than 5%, reject the null hypothesis
NTP- Null hypothesis, test, pvalue
Test of significance

6. How do you decide which TOS?
Test of significance

7. How to decide a TOS Parametric or Non parametric tests?
Association or correlation?
Test of significance

8. Parametric Vs Non parametric
Look for normality of data
Histogram and look for normal bell curve
Test of significance

9. Another rule of thumb
if the SD is more than half of the mean, then it is not normally distributed
Normal data: Parametric
Skewed data: Non parametric data
Test of significance

10. Association and correlation
Test of significance

11. Association and correlation
Concept
Is relationship between two continuous numerical variables
Example
Is smoking associated with lung cancer?
one increases other decreases (weight & hours of exercise)
Tests
Chi square, Student t test, paired t test, ANOVA
Pearson’s
Test of significance

12. How to choose test for association
Test of significance

13. Dependant and independent variable Consider the RQ: Is smoking associated with lung cancer?
Test of significance

14. Look at the dependant variable/ Outcome variable
Type of data
Numerical data
How many groups?
3 or more
ANOVA
2 groups
2 separate groups
Student t test
1 group
Before and after
Paired t test
Category
Chi-square test
Test of significance

15. Test will generate a p value
What does that mean?
Test of significance

16. What is the test actually doing?
Zone of acceptance
Zone of rejection
Test of significance

17. My data
Test of significance

18. Reporting TOS in papers /inference
Smoking and Lung cancer
Proportion of smokers is higher in patients with lung cancer(55%) when compared to normal people(21%) and it is statistically significant (p<5%).
Smoking is associated with Lung cancer (p<5%).
Test of significance

19. Lets apply RQ:Is smoking associated with lung cancer Null hypothesis
Test?
Test of significance

20. Lets apply RQ: Is birthweight associated with neonatal death?
Hypothesis
Test
Test of significance

21. Lets apply
RQ: Drug A or Drug Bod Drug C is better in patients with HTN?
Hypothesis
Test
Test of significance

22. Lets apply
RQ: will health education improve the knowledge of diabetes?
Hypothesis
Test
Test of significance

23. Numerical data RQ: Is birthweight associated with neonatal death?
Mean birthweight of babies who died is significantly lower as compared to babies who survived (1.45kg Vs 2.9kg,p<5%)
RQ: will health education improve the knowledge of diabetes?
Mean knowledge score was higher intervention was higher/MKS improved significantly after intervention and this was statistically significant
Test of significance

24. Another scenario Smoking, age, alcohol, blue shirt : Lung cancer
Smoking Lung cancer
Age Lung Cancer
Alcohol Lung Cancer
Blue shirt Lung cancer
Concept of independent association: Solving by Regression
Test of significance

25. Non parametric tests
If the data is not normally distributed, we will use a non parametric counterpart
Test of significance

26.
Test of significance

27. Errors Truth is No association : You say association : (Type 1)
Blue shirt is associated with cancer
Truth is Association : You say No association (Type 2)
Smoking is not associated with lung cancer
When can these happen?
Test of significance

28. Correlation
Concept : association between two continuous numerical variables
one increases other decreases (weight & hours of exercise)
One increases other increases (weight & BMI)
Test : Pearson's correlation(r)
Test of significance

29.
Test of significance

30.
Test of significance

31. Recap Types of data Algorithm for test Independent association
Correlation
Test of significance

32.
Test of significance