Data Processing, Demography, Data Presentstion, and Measures of Central Tendency

Measure of central tendency

a typical value or a representative value of a set of data that described the performance of the group

Mean

commonly used measure of the center of data, arithmetic average

Median

divides the scores in the distribution into two equal parts, middle score/ 50th percentile

Mode

scores that occurred most in the distribution

Unimodal

distribution of scores that consists of only one mode

Bimodal

distribution of scores that consists of two modes

Trimodal

distribution of scores that consists of three modes

Multimodal

distribution of scores that consists of more than three modes

Measures of Central Location

tells where a specific data value falls within the data set or its relative position in comparison with other data values

Quartiles

divides ranked scores into four equal parts

Deciles

divides ranked data into ten equal parts

Percentiles

divides ranked data into one hundred equal parts

Fractiles

partitions data into approximately equal parts

Measures of Variability

describe the spread or the dispersion of a set of data, how the scores are scattered around the central point

Range

the difference between the largest and the smallest values in a set of data

Interquartile range

ranges of values between the first and third quartiles

Mean absolute deviation

average of the absolute deviations from the mean

Population variance

average of the squared deviations from the arithmetic mean

Population standard deviation

square root of the variance

Z-score

represents the number of standard deviations a data value falls above or below the mean

Coefficient of Variation

ratio of the standard deviation to the mean, expressed as a percentage

Skewness

Extreme values in one side of a distribution

Kurtosis

peakedness of a distribution

Negatively skewed

If Sk < 0, skewed to the left

Symmetric

Sk = 0, not skewed

Positively skewed

Sk > 0, skewed to the right

Leptokurtic

high and thin

Mesokurtic

normal in shape

Platykurtic

flat and spread out

Demography

the empirical, statistical, and mathematical study of human populations

Count

absolute number of a population or any demographic event occurring over a specified period and area

Ratio

A single number that represents the relative size of two numbers

Proportion

a special type of ratio in which the numerator is part of the denominator

Rate

measure of the frequency of (new) demographic events in a given period of time

Census

the total process of collecting, compiling, and publishing demographic, economic, and social data pertaining to all persons in a country at specified times

De Jure (by right)

assign individuals to the place of their usual residence regardless of where they were actually enumerated during the census

De Facto (by fact)

allocate individuals to the area where they were physically present at the census data regardless of where they usually live

Sample surveys

obtain information from only a subset of the entire population

Vital Registration systems

Continuous recording systems of vital events as they occur in the population

Recall

Demography focuses on the following

• Population size, composition, distribution

• Changes in population size and compo

• Components to these changes

• Factors affecting these ocmponents

• Consequences of these changes

Population size

frequency or count of members in a population

Population distribution

refers to the location of the population in geographic subdivisions of a given area

Population density

total population/land area covered by the population

Urban-rural distribution

Distribution of the population according to place of residence classifies into rural and urban areas

Crowding index

more specific measure of density

Density of occupancy

number of persons per unit of floor area

Population composition

description of measurable characteristics of the population

Sex ratio

number of males : number of females

Sex structure

compares the sex ratio across different categories/levels of another characteristic

Median age

the middle-most age in a population arranged from youngest to oldest

Age dependency ratio

relates the size of the dependent segment of the population to the economically productive age-group of the population