Contains Research methodology might be useful to medical and paramedical UG and PG students pursuing Research

1. Sampling
fundamentals
D.A. Asir John Samuel, MPT (Neuro Paed),
Lecturer, Alva’s college of Physiotherapy,
Moodbidri
Dr.Asir John Samuel (PT), Lecturer, ACP

2. Some fundaments definitions
• Population
- Collection of all the units that are of interest to
the investigator
• Sample
- Representative part of population
• Sampling
- Technique of selecting a representative group
from a population
Dr.Asir John Samuel (PT), Lecturer, ACP

3. Some fundaments definitions
• Sampling error
- The difference that occurs purely by chance
between the values of sample statistic and
that of the corresponding population
parameter
Dr.Asir John Samuel (PT), Lecturer, ACP

4. Need for sampling
• Only feasible method for collecting information
• Reduces demands on resources (time, finance,.)
• Results obtained more quickly
• Better accuracy of collected data
• Ethically acceptable
• Only way when population contains infinite
members Dr.Asir John Samuel (PT), Lecturer, ACP

5. Sampling distributions
• Parametric tests
• Non parametric tests
Dr.Asir John Samuel (PT), Lecturer, ACP

6. Chi-square Test (x2)
• Variables of interest are categorical
(quantitative)
• To determine whether observed difference in
proportion b/w the study groups are
statistically significant
• To test association of 2 variables
Dr.Asir John Samuel (PT), Lecturer, ACP

7. Chi-square Test-Assumption
• Randomly drawn sample
• Data must be reported in number
• Observed frequency should not be too small
• When observed frequency is too small and
corresponding expected frequency is less than
5 (<5) – Fischer Exact test
Dr.Asir John Samuel (PT), Lecturer, ACP

8. Test statistic
x2 = ε(O-E)2/E
O – observed frequency
E – expected frequency
Dr.Asir John Samuel (PT), Lecturer, ACP