## Epidemiological_Study

study_id | name | start_date | end_date
--- | --- | --- | ---
1 | COVID-19 Study | 2020-03-01 | 2021-06-01
2 | Flu Study | 2020-08-01 | 2021-07-01
3 | Diabetes Study | 2020-04-01 | 2021-09-01
4 | Heart Disease Study | 2020-05-01 | 2021-10-01
5 | Obesity Study | 2020-06-01 | 2021-11-01

## Methods

method_id | method_name
--- | ---
1 | Survey
2 | Blood Test
3 | Questionnaire
4 | Physical Exam
5 | Imaging

## Study_Participants

participant_id | epidemiological_study_id | first_name | last_name | age
--- | --- | --- | --- | ---
| (→ Epidemiological_Study.study_id) |  |  |
1 | 1 | John | Doe | 30
2 | 1 | Jane | Smith | 25
3 | 2 | Bob | Brown | 40
4 | 2 | Alice | Green | 35
5 | 3 | Tom | White | 50

## Diseases

disease_id | disease_name
--- | ---
1 | Covid-19
2 | Influenza
3 | Type II Diabetes
4 | Coronary Heart Disease
5 | Obesity

## Diagnoses

diagnosis_id | participant_id | disease_id | date_of_diagnosis
--- | --- | --- | ---
| (→ Study_Participants.participant_id) | (→ Diseases.disease_id) |
1 | 1 | 1 | 2020-04-01
2 | 1 | 2 | 2020-04-15
3 | 2 | 3 | 2020-05-01
4 | 2 | 4 | 2020-05-15
5 | 3 | 5 | 2020-06-01

## Epidemiological_Study_Methods

epidemiological_study_id | method_id
--- | ---
(→ Epidemiological_Study.study_id) | (→ Methods.method_id)
1 | 1
1 | 2
2 | 3
2 | 4
3 | 5
2 | 1
3 | 1
4 | 1
5 | 1