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Standard Deviation & Standard Error (SD & SE)

The difference between the terms ‘Standard Deviation (SD)’ and ‘Standard Error (SE)’ may be confusing.
Both SD and SE are measures of variation but of two DIFFERENT factors. What are they?
Let us take an example:
We want to weigh a population of 10,000 workers in a factory.
The ideal way to do that would be to:
Weigh each one of the population of 10,000
Calculate the mean weight of the population i.e. Add up all the 10,000 weights and divide by 10,000.

Clinical Grading of Pallor

Mild: Conjunctival pallor and/or of tongue
Moderate: Conjunctival pallor and/or of tongue + palmer pallor
Severe: Conjunctival pallor and/or of tongue + palmer pallor + pallor of palmar creases.

Regina D et al. Correlation of pallor with hemoglobin levels and clinical profile of anemia in primary and middle school children of rural Telangana. Int J Contemp Pediatr. 2016 Aug;3(3):872-877

Food Pyramid

The “Food Pyramid” or “Food Guide Pyramid” was introduced by the USDA (US Department of Agriculture) in 1992.
It is meant as a reference for planning a balanced diet everyday.
It defines five groups of foods:
1. breads, cereals, pasta and rice;
2. fruits and vegetables;
3. dairy products; eggs, fish, legumes,
4. meat and poultry;
5. alcohol, fats and sugars –
• Sugars mean ADDED sugar.
• Fat and sugars come mostly from the fats, oils and sweets.


• 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

Demographic cycle

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


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