# Nigeria - National Survey of Agricultural Export Commodities 2005, Second round

Reference ID | NGA-NBS-AGREXP-2005-v1.0 |

Year | 2005 |

Country | Nigeria |

Producer(s) | National Bureau of Statitics (NBS) - Fedral Government of Nigeria (FGN) |

Sponsor(s) | National Bureau of Statitics - NBS - Technical Support Central Bank of Nigeria - CBN - Funding |

Metadata | Documentation in PDF Download DDI Download RDF |

Created on | Oct 18, 2010 |

Last modified | Dec 02, 2013 |

Page views | 400352 |

Downloads | 214739 |

Sampling

Sampling Procedure

The survey covered all states of the Federation and the Federal Capital Territory (FCT). The number of LGAs allocated to each state for sampling varied from a minimum of 3 to a maximum of 9 based on the number of export crops grown as well as on the intensity of cultivation and corresponding output.

In all, 192 LGAs were mapped out for sampling nationwide while 10 Enumeration Areas were in turn listed for sampling in each LGA. This brought the total number of EAs initially slated for sampling nationwide to 1920.

In each EA, 10 Housing Units (HUs) were to be selected in order to cover a total of 19,200 HUs.

Deviations from Sample Design

192 LGA's were selected nationwide (see details in 2.1). But due to logistics problems, the number of LGA's actually covered was about 182.

Response Rate

On a national basis the 2005 survey achieved a response rate of about 77.66% at Housing Unit level.

Weighting

The formula adopted in calculating the design weights for the survey data (sample results) were as follows:

(i) The probability of selecting an EA within a state was obtained by dividing the total number of EAs sampled in a

state by total number of EAs in that particular state. Let this be represented by fj. That is,

fj = (Total Number of EAs sampled in a state)/(Total Number of EAs in that particular State)

(ii) Likewise, the probability of selecting an housing unit (HU) within an EA was obtained by dividing the total number

of housing units selected in an EA by the total number of housing units (HUs) listed in that particular EA. Let this be

represented by fk. That is,

fk = (Total Number of HUs selected in an EA)/(Total Number of HUs listed in that particular EA)

Then the product (fj) x (fk) represented by f is the sampling fraction for each of the corresponding study unit (Enumeration Area) for all the 1,920EAs canvassed throughout the 36 states of the Federation and FCT, Abuja. The inverse of the sampling fraction is known as the design weight and was applied accordingly to all the study units.

Mathematically,

Design weight = ((Total number of EAs in a state)/(Total number of EAs sampled in that particular state)) X ((Total Number of HUs listed in an EA)/(Total Number of HUs selected in that particular EA))

The above value was obtained for each of the 1,920 EAs canvassed throughout the 36 states of the Federation and FCT, Abuja.

The weight (Rf) was calculated and attached to the data