## Material and methods part 1

## Material and methods part 2

## MATERIAL AND METHODS LAYOUT

## CROSS SECTION STUDY

**Outline**

- Population/patients
- Screening
- Procedures/Survey
- Definition of variables
- Ethical clearance
- Statistical analysis

**Population/patients**

- Provide a brief outline of
- study population
- clinical services in question
- Study location/ area

- participants
- study areas and disease/ case distribution
- Location /area where the participants were recruited
- Hospital base
- Population base

- Duration of study: for e.g. From Nov 1, 2003, to Sept 30, 2014,

**Screening/Survey**

- screening / survey method is described with references
- staff qualification an training
- Quality-control measures to check data completeness and consistency.
- Define questionnaire/investigation/procedures

**Procedure**

- Preliminary data
- demographic data
- questionnaires
- surveys
- examination

- cases:
- diagnostic criteria
- inclusion and exclusion criteria

- Outcome
- The primary endpoint
- Secondary end points

**Ethical clearance**

- Written informed consent
- Study protocol was approved by Regulatory Agency/ethics committee
- Study was done in accordance with the principles of the Declaration of Helsinki and the International Council for Harmonization Good Clinical Practice guidelines.

**Definition of variables**

- Definition of variables
- Study variables
- Outcome variables

**Statistical analysis**

- Null hypothesis
- Power and alpha
- Sample size calculation and expected power of the study.
- Statistical methods adopted to calculate

- The primary endpoint
- primary analysis
- categorical exposure variables(association between outcome and intervention)
- Odd ratio
- Confidence interval, Confidence level

- Comparative evaluation of any study variable to predict disease
- logistic regression models
- model-fitting info

- Secondary end points

- categorical exposure variables(association between outcome and intervention)
- Data analysis software

- primary analysis

## Sample size calculation

**Confidence level: 95% p < 0.05, Z= 1.96****Confidence level: 99% p < 0.001, Z= 2.58**

## CASE CONTROL STUDY

**What is a case control study? **

**Example of case control study**

**Outline**

- Population/patients
- Cases and control
- Procedures/Survey
- Definition of variables
- Ethical clearance
- Statistical analysis

**Population/patients**

- Provide a brief outline of
- study population
- clinical services in question
- Study location/ area

- participants
- study areas and disease/ case distribution
- Location /area where the participants were recruited
- Hospital base
- Population base

- Duration of study: for e.g. From Nov 1, 2003, to Sept 30, 2014,

- Sample size
- Sample size
- Cases
- control

- randomization
- Matching criteria for cases and controlling
- Matching ratio between cases and control
- Recall bias

**Cases and control**

- Case and control
- Inclusion criteria
- Exclusion criteria

- Matching criteria (in the video below)
- Matching ratio

**Matching criteria**

**Procedure**

- Preliminary data
- demographic data
- Cases and control

**Variables**

- Dependent variable /outcome variable
- Independent variables /comorbidities

**Ethical clearance**

- Written informed consent
- Study protocol was approved by Regulatory Agency/ethics committee
- Study was done in accordance with the principles of the Declaration of Helsinki and the International Council for Harmonisation Good Clinical Practice guidelines.

**Descriptive analysis of the study variables**

- qualitative variables
- frequencies and percentages

- quantitative variables
- means and SD

- Differences between means
*t*test for independent data

- To compare proportions within the group of cases,
- The χ
^{2}test or the Fisher exact test for expected values of less than 5.

- The χ

**Odd ratio**

- to compare the odds of developing primary study outcome( dependent variable) for each co-morbid condition(independent variable)
- Crude odds ratios (ORs) and 95% confidence intervals (CIs)
- univariate logistic regression analysis for both groups.

- The resulting ORs were also adjusted for matching criteria.
- The resulting ORs were also adjusted for matching criteria for case and control.

**Calculating the odds ratio**