PROBABILITIES OF LIVING:

The probability that a person age “x” will die in the next year is represented by the symbol q_x. The probability that a person age “x” will live to reach (x + 1) is represented by the symbol “p_x”.

That is. P with a subscript x. it is read “p sub x” or simply “p x”. An example would be p₃₄ which is read “p sub 34” or “p 34”. It means the probability that a person age 34 will live to reach age 35, that is, will be alive for at least one whole year.

In general terms, it may be said that if the number living at age (x + 1) is divided by the number living at age x, the result will be the probability that a person age x will live to reach age (x + 1). In equation form, this is written as:

RATES AND RATIO

 RATIO:

 Ratio measures change in “X” per unit change in”y”.

Ratio = x/y

There are different types of ratio:

i)                    When we have numerator and denominator belongs to the same population.

ii)                   When we have numerator and denominator belongs to the different population (universe). We call the ratio as proportion (specific name of ratio).

                                Proportion= x/x+y

Proportion tends is equal to zero if x=0 and proportion is equal to 1 if y=0.

Ratio indicates the relative magnitude of a numerator and denominator.

MORTALITY & FERTILITY

MORTALITY:

Mortality rate (word mortality comes from mortal, which originates from Latin Mors, means death) is the number of deaths (from a dieses or in general).Per thousand people and typically reported on an annually basis. It is distinct from mortality rate, which refers to the no of people who have a dieses compared to the total no of people in a population. The United Nations and World Health Organization have proposed following definition of death or mortality.

“The mortality rate is the ratio of the number of deaths during a given time period per 100,000 live births during the same period of time”.

LIFE TABLE

A life table presents a set of tabulation that describes the probability of dying, the death rate, and the number of survivals for each age or age group. Accordingly, life expectancy is at word is an outward of a life table.                                     

In actuarial science a life table (also called the mortality table or actuarial table) is a table which shows for a person at each age, what is the probability is that they die before their next birthday. From this starting point, a no of statistics can be derived and also included in the table.

ERROR IN AGE REPORTING AND THEIR METHODS

In demographic data the most important and common error is committed in recording of ages. Ages are recorded in whole numbers in completed years. Extract date of birth are seldom asked, even if exact date of birth are known, the date is tabulated with a reference to date in incomplete year which creates biased over above ages are misstated due to conscious acts and same times unconsciously wrong ages are recorded. Studies of various ages data revealed that following type of misstatement of ages are usually recorded.

MEASUREMENT OF ERRORS IN DEMOGRAPHIC DATA

Methods of measurements of errors have been developed for census statistics; however can equally be used in vital statistics registration.

Response error is a broad term which includes both errors of coverage and error of content. The sampling theory assumed the census or survey or VSR records collected at time period are regarded as one of the series of trials, collection of responses which would vary from trial to trial. This hypothesis further assumed that the trials have been conducted under the same conditions and that they are independent of each other.

Various indices, measuring levels of errors can be calculated through this table:

ERRORS IN DEMOGRAPHIC DATA

Despite the care taken to ensure the quality of the data collected by enumeration and registration, it will some time give obvious indications of errors in basic information. Usually errors in censuses and vital statistic registration (VSR) are of two types: