1. 1 Bandit Thinkhamrop, PhD.(Statistics) Dept. of Biostatistics & Demography Faculty of Public Health Khon Kaen University Formulation of a research Using Backward approach

2. 2 Formulating a research question Use a funnel type of logical Outline what is the problem, what has been known and unknown, identifying knowledge gap, address a question of the study: –The nature and scope of the problem –Previous findings –The gap of the knowledge –The research question (hypothesis) Source: https://www.ctnbestpractices.org/edu/crwseries/ Source: https://www.ctnbestpractices.org/edu/crwseries/

3. 3 Core Questions Begin at the destination 1. What is the research question? 2. What is the expected answer or the conclusion? 3. What is the expected magnitude of effect to be used as the basis of the conclusion? 4. What is the implication of the findings? 5. What could influence the validity of the data and how to avoid them? 6. How to analyze the data to get the targeted magnitude of effect? 7. What is the required sample size?

4. 4 1. What is the research question? State the research question If more than one questions, select one to be the primary research question Example: –What are predictors of low birth weight? –What is the efficacy of the HIV vaccine?

5. 5 2. What is the answer or the conclusion? State the expected the answer to the primary research question Example: –Low BMI of mother and not received ANC increase risk of low birth weight –HIV vaccine can prevent HIV infection

6. 6 3. What is the expected magnitude of effect to be used as the basis of the conclusion? Specify type of the primary outcome variable Specify type of the magnitude of effect: –Absolute effect (mean or mean difference, proportion or proportion difference, rate, correlation coefficient, kappa, etc.) –Relative effect (relative risk, odds ratio, incidence rate ratio, or hazard ratio) Specify its expected magnitude to be determine and the minimum magnitude that is meaningful

7. 7 4. What is the implication of the finding? Specify benefits of the finding State an expected recommendation

8. 8 5. What could influence the validity of the data and how to avoid them? Describe briefly how the magnitude of effect would be obtained Describe how it could be wrong by considering these sources of biases: Selection bias Information bias Confounding bias Describe how to avoid, prevent, or minimize them

9. 9 6. How to analyze the data to get the targeted magnitude of effect? Select statistical methods based on type of the primary outcome and the study design Describe how to analyze the data, focusing on the primary research question Construct key dummy tables for presentation of the results

10. 10 7. What is the required sample size? Stick to the primary outcome Identify and review the magnitude of effect and its variability that will be used as the basis of the conclusion of the research. Identify what statistical method that will be used to obtain the main magnitude of effect. Calculate the sample size Evaluate if this sample size would provide a precise and conclusive answer to the research question by analyze the data as if it is as expected. Describe how the sample size is calculated with sufficient details that allow explicability.