Organised by

1
Workshop on 2010 World Programme on Population
and Housing Censuses Census Evaluation and Post
Enumeration Surveys

• Organised by
• United Nations Statistics Division (UNSD) in
  conjunction with the African Centre for
  Statistics
• Addis Ababa, Ethiopia, 14 18 September 2009

2
Country ExperiencePresented by

• Mrs. N.Gujadhur
• Central Statistics OfficeMauritius
• September 2009

3
(No Transcript)
4
Islands of Mauritius and Rodrigues

• Capital Port Louis
• Population 1.28 mn
• Population growth rate 0.5
• Area 2,040 km2
• Population density 625 persons/km2
• Monetary unit MRupees
• Literacy rate 85
• Languages English French

5
Outline

• Census taking in Mauritius
• Evaluation of the 2000 Census
• Previous Census evaluations
• Census Errors
• Demographic Methods for census evaluation

6
Census taking in Mauritius

• 1st complete Census in the Island of Mauritius
  was undertaken in 1735
• Since then, censuses have been taken in 1846,
  1851 and every 10 years up to 1931.
• After the 2nd World War, the ten-yearly programme
  was resumed and Housing and Population censuses
  were undertaken in
• 1952, 1962, 1972,
• 1983, 1990 and 2000
• Next census gt 2011

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Census Organisation

• The 2000 Housing Population Census (HPC) was
  conducted in the Island of Mauritius, Rodrigues
  and Agalega.
• 1st round - Housing Census
• Chief Enumerators enumerated all buildings,
  housing units, households, commercial
  establishments, hotels, institutions etc.
• 2nd round - Population Census
• Enumerators enumerated all persons present on
  census night as well as usual residents who were
  away on census night.

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2000 Census Data Evaluation

• Census Evaluation
• Main objectives
• To identify the types sources of errors
• To measure accuracy of data
• To adjust the data where necessary
• Different methods of evaluation
• Matching studies - e.g Post Enumeration Surveys
• Non-Matching studies
• Mauritius gt Census evaluation through
  Demographic methods using previous censuses and
  comparisons with administrative data.

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2000 Census Data Evaluation

• Previous Demographic Census Evaluation
• 1st census for which data evaluation was carried
  out gt 1952.
• 1962 and 1972 gt census evaluated by Experts
  appointed under the UN Programme of Technical
  Co-operation.
• 1983 and 1990 gt census evaluated by local staff
  under the guidance of UNECA Expert.
• 2000 census gt census data evaluation were
  carried out by local staff.

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2000 Census Data Evaluation

• Census Errors
• Census gt massive data collection, errors may
  creep in at any stage of data collection and
  processing.
• These errors are-
• (i) Coverage Error gt error in the count of
  persons /housing units
• (ii) Content Error gt error in the recorded
  characteristics of those persons that
  were enumerated in the Census

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2000 Census Data Evaluation

• (i) Coverage Error
• Coverage Error gt non-sampling error that may
  have occurred during 2000 Census.
• Omission - Omitting a unit that should have
  been included.
• Duplication - Including a unit more than once.
• Erroneous - Including a unit that should not
  have been included.

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2000 Census Data Evaluation

• Demographic methods used in Mauritius for
  detecting coverage error - C2000
• 1. Balancing equation by sex
• 2. Growth rate
• 3. Age and sex composition
• 4. Sex ratio
• 5. Child-woman ratio
• 6. Population Estimates
• 7. External consistency checks

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2000 Census Data Evaluation

• 1. Balancing equation by sex
• Comparing the 2000 Enumerated Population with the
  Expected population based on the 1990 census.
• So, when compared to international norms, a net
  deficit of 0.4 is acceptable.

Expected 2000 Population Enumerated Population -2000 Census Excess of Enumerated over expected
1990 Enumerated Pop. 1,056,660
1990 - 2000
Live Births 211,689
- Deaths (75,425)
Arrival of Mauritian Residents 1,111,526
- Departure of Maurt. Residents (1,120857)
Expected Population-Year 2000 1,183,773
Enumerated Population 1,178,848
Excess - Enumerated /Expected -4,925 (-0.4)
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2000 Census Data Evaluation

• 2. Growth Rate
• Inter-censal growth rates can also help in the
  evaluation of census data.
• A low rate of growth would be suggestive of net
  under enumeration in the 2ndcensus relative to
  the 1st census or over enumeration of the 1st
  census relative to the 2nd census.
• In Mauritius, the natural Growth rate shows a
  smooth decline over time.

Inter -censal period Net Growth Rate () Natural Growth Rate()
1962 - 1972 1.97 2.39
1972 - 1983 1.48 1.81
1983 - 1990 0.79 1.30
1990 - 2000 1.10 1.22
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2000 Census Data Evaluation

• 3. Age and sex Composition
• The age and sex distribution () of the
  population for different censuses is also used to
  compare the Enumerated Population.
• A decrease in the proportion of children
  aged(04) and
• (5 14) and a general increase in the
  proportion aged 60 years and above can be
  observed from one census to another.

Age Group Census Census Census Census
Age Group 1972 () 1983 () 1990 () 2000 ()
0 - 4 12.4 11.7 9.2 8.0
5 - 14 28.0 20.8 20.5 17.2
15 44 42.7 49.6 51.1 50.8
45 59 11.0 10.9 10.9 14.9
60 5.9 7.0 8.3 9.1
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2000 Census Data Evaluation

• 3. Age and Sex Composition (contd)
• A Population Pyramid showing the 1990 and 2000
  population by age and sex.

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2000 Census Data Evaluation

• 4. Sex ratio
• The sex ratio is defined as the number of males
  per 100 females. It measures the composition of
  the population enumerated at a particular age
  with respect to sex.
• Unless affected by errors, the sex ratio of the
  enumerated census population, should be
  relatively stable from one census to another.
• Significant departures from this pattern would
  indicate coverage error in the enumerated
  population.

Census Year 1962 1972 1983 1990 2000
Sex ratio 100.8 100.2 99.2 99.8 98.1
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2000 Census Data Evaluation

• 5. Child Woman ratio
• The Child-woman ratio is defined as the number
  of children aged 0-4 years per 1,000 women in
  the age group 15 44 years.
• The childwoman ratio are in line with the
  fertility decline registered over the past
  decades.

1983 1990 2000
Republic of Mauritius 473.7 363.3 316.7
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2000 Census Data Evaluation

• 6. Population Estimates
• This method of evaluation entails the projection
  of the 1st census forward in time to the 2nd
  census based on estimated
• mortality rates
• fertility rates
• net migration rates
• These rates were applied to the 1990 Population
  Census and the expected population derived in
  this manner was then compared with the 2000
  enumerated population.

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2000 Census Data Evaluation

• 7. External Consistency Checks
• (i) Vital Registration System
• Mauritius has a very good vital registration
  system. Counts of persons derived from Civil
  Status Division of Mauritius is complete, and
  provide valuable information on the accuracy of
  the census enumeration.
• Births and deaths registration has been used to
  assess census coverage of the population at
  youngest ages, which are usually
  under-enumerated.
• For the 2000 Population Census, adjustments for
  the under-enumeration of young children aged 0-9
  ( 4,456 male and 3,569 female) were made to
  compensate this population coverage.

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2000 Census Data Evaluation

• (ii) Education Statistics
• Comparison of Population Census with education
  statistics is another external source of data
  with which Census data was compared.
• Data from the 2000 survey conducted in March by
  the Ministry of Education was compared with
  census data on students currently going to
  school.

Male Male Male Female Female Female
Age Group 2000 Census Data School Statistics Difference 2000 Census Data School Statistics Difference
5 - 9 52,702 56,172 -6.2 51,860 55,147 -6.0
10 - 14 44,862 43,104 4.1 44,222 42,770 3.4
15 - 19 25,952 23,192 11.9 25,635 23,095 11.0
5 - 19 123,516 122,468 0.9 121,717 121,012 0.6
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2000 Census Data Evaluation

• (iii) Housing Census Count
• Comparison of Population Census with Housing
  Census count
• Housing Census was conducted from February to
  April 2000 Population Census was taken at
  the beginning of July 2000.

2000 Housing Census -February-April 2000 Population - July Difference
Private Households 297,881 296,832 0.4
Population 1,168,495 1,165,570 0.3

• Thus, minor differences of around 0.3 in the
  population figures and 0.4 in the household
  figures are observed.

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2000 Census Data Evaluation

• Content Errors
• Age profile of the population is one of the basic
  information. It is therefore very important to
  evaluate the accuracy of the age distribution.
• (i) Digit Preference
• Digit preference or age heaping is a common error
  that occurs in the age reporting.
• It appears that there is a slight preference for
  the digit 0 among both males and females.

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2000 Census Data Evaluation

• (i) Digit Preference (contd)
• The table below shows the most preferred digits
  by sex -1990 2000 Censuses
• It is observed that preference for digit 0 has
  persisted from 1990 to 2000 Census. However, the
  preferred digit has shifted from 5 in 1990 to 2
  in 2000 for female.

Census Year Index Republic of Mauritius Republic of Mauritius
Census Year Index Male Female
1990 Myers 0,5 5,0
P.P.I 0,5,6 5,0,2
2000 Myers 0 0,2
P.P.I 0,9 0,2
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2000 Census Data Evaluation

• (i) Digit Preference (contd)
• The table below shows Indices for digit
  preference -1990 2000 Censuses
• Both the Myers Index and the Preference Pattern
  Index (PPI) show no marked digit preference in
  age reporting at the Census. (0 no digit
  preference 180 for absolute digit preference)

Digit Republic of Mauritius Republic of Mauritius Republic of Mauritius Republic of Mauritius
Digit Male Male Female Female
Digit Myers P.P.I Myers P.P.I
2000 Index 2.0 2.3 1.9 2.1
1990 Index 2.4 2.9 2.9 3.3
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2000 Census Data Evaluation

• (ii) Vertical consistency checks for
  age-reporting error
• To quantify the degree of age - sex reporting
  errors, various indices such as the Age Ratio
  Score the Sex Ratio Score and the UN Age-Sex
  Accuracy Index/UN Joint Score have been
  calculated for the population aged under 70
  years.
• The census data is considered to be accurate,
  inaccurate or highly inaccurate depending on
  whether the UN Age-Sex Accuracy Index is under
  20, 20 - 40 or 40 and over respectively.
• Thus, the 2000 census data was considered as
  accurate.

UN Age - Sex Accuracy Index UN Age - Sex Accuracy Index UN Age - Sex Accuracy Index
Census 1990 2000
UN Joint Scores 17.3 18.3
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2000 Census Data Evaluation

• (iii) Diagonal consistency checks
• The quality of census data can also be assessed
  by the analysis of cohort survival ratios.
• The cohort survival ratio is the ratio of the
  population of a particular age group at a given
  census to the population ten years younger in
  the preceding census. The survival ratio is
  expected to decrease smoothly with increasing
  age.

Cohort survival ratios Cohort survival ratios Cohort survival ratios Overall survival ratios Overall survival ratios Overall survival ratios
Age Male Female Age Male Female
0-4 0.9719 0.9842 0 0.9130 0.9369
5-9 0.9815 0.9848 5 0.9051 0.9309
10-14 0.9639 0.9944 10 0.8957 0.9244
15-19 0.9495 0.9809 15 0.8852 0.9140
20-24 0.9531 0.9864 20 0.8753 0.9041
25-29 0.9615 0.9698 25 0.8600 0.8891
30-34 0.9598 0.9724 30 0.8345 0.8704
35-39 0.9479 0.9718 35 0.7986 0.8441
40-44 0.9225 0.9618 40 0.7492 0.8071
45-49 0.8777 0.9326 45 0.6941 0.7636
50-54 0.8288 0.9091 50 0.6389 0.7182
55-59 0.7495 0.8504 55 0.5744 0.6609
60-64 0.6431 0.7586 60 0.5034 0.5970
65-69 0.5350 0.6843 65 0.4174 0.5175
70-74 0.3988 0.5501 70 0.3122 0.4083
75 0.2211 0.3065 75 0.2211 0.3065
All ages 0.9130 0.9369      
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Thank you
For additional information, go to http//www.gov.
mu/portal/sites/ncb/cso/report/hpcen00/census3/ind
ex.htm