• NOISE- Unwanted sound
• Come to be a major “stress factor” in today’s life
– Noise Pollution = unwanted or excessive sound that can have damaging effects on human health,
• Sources of noise are varied:
– Automobiles
– Factories
– Air crafts etc.
• Levels particularly high around:
– Railway junctions,
– Bus depots
– Airports
– High Traffic areas etc.
• Noise has 2 characteristics:
1. Intensity or loudness
2. Frequency
Studying the world population since 1650 suggests that demographic transition of a nation involves of 5 stages.
These stages constitute the “demographic cycle”.
(1) FIRST STAGE (High stationary)
It is characterized by both
*A high birth rate and
*A high death rate
Therefore the population remains stationary
It is seen when the country is economically most weak
India was in this stage till 1920
(2) SECOND STAGE (Early expanding)
It begins with the
*Declining of death rate while
Under construction!
Under construction!
Under construction!
Decades after the development of vaccines and antibiotics, infectious diseases have not disappeared as was predicted.
For the prevention and control of Infections, knowledge of its epidemiology is needed.
Definitions are critical for any type of epidemiological action e.g.
*Disease reporting,
*Measurement of mortality and morbidity
The steps lead to the calculation of the value of. x^2 for the study data
Value of the calculated x^2 is referred to the x^2 -table -where the ‘p’ value seen
Test can be applied:
a) On qualitative data
b) Random sample
c) The lowest observed frequency in all the cells is 5 or more
d) None of the observed values is zero
Advantages (over ‘SE of diff bet two means’ test):
a) Equally applicable for small samples and large samples
b) The test can be used even if there are >2 categories
Suspect case
A. A patient with acute respiratory illness (fever and at least one sign/symptom of respiratory disease (e.g., cough, shortness of breath), AND with no other etiology that fully explains the clinical presentation AND a history of travel to or residence in a country/area or territory reporting local transmission of COVID-19 disease during the 14 days prior to symptom onset.
OR
B. A patient with any acute respiratory illness AND having been in contact with a confirmed or probable COVID19 case in the last 14 days prior to onset of symptoms;
Standard Error of Difference between Two Proportions 
(blog under construction)
Chi-square test or 
(blog under construction)
Unpaired-‘t’ test (or simply, the't'-test) (blog under construction)
‘Z’ test (blog under construction)
Paired 't'-test– For Paired values (blog under construction)
Tests of significance are used for comparison between two or more groups
The difference may be just by chance OR
The may be an actual difference between the two (or more) groups and there may be a reason for that
