COLLEGE OF EDUCATION AND EXTERNAL STUDIES

SCHOOL OF CONTINUING AND DISTANCE EDUCATION

DEPARTMENT OF EXTRA-MURAL STUDIES.

LDP603: RESEARCH METHODS GROUP ASSIGNMENT

GROUP 5 QUESTION: DISCUSS THE VARIOUS PROBABILITY AND NON-PROBABILITY SAMPLING TECHNIQUES USED IN RESEARCH.

GROUP 5 (A) MEMBERS

|S/NO |SURNAME |OTHER NAMES |REG. NO |SIGNATURE | | |GICHOHI |BENARD MUTAHI |L50/64207/2010 | | | |AYUYA |ANDREW ANGAYA |L50/64684/2010 | | | |WAHINYA |COSMUS KIRORI |L50/63829/2010 | | | |OSUMBAH |LILIAN ACHIENG’ |L50/64090/2010 | | | |CHEBOI |ANDREW KIMUTAI |L50/64237/2010 | | | |OGUDI |PETER ONYANGO |L50/63654/2010 | | | |NJAU |JOSEPH NJENGA |L50/65416/2010 | | | |NAMARA |FRANK |L50/65510/2010 | | | |MUTISYA |CHRISTOPHER MUNYAO |L50/66193/2010 | | | |MAINA |MARTHA GATHONI |L50/64247/2010 | |

LECTURER: DR. CHRISTPOHER GAKUU

JANUARY 2011

1. Introduction

Sampling is that part of statistical practice concerned with the selection of a subset of individual observations within a population of individuals intended to yield some knowledge about the population of concern, especially for the purposes of making predictions based on statistical inference. Sampling is an important aspect of data collection. Researchers rarely survey the entire population for two reasons (Adèr, Mellenbergh, & Hand, 2008): the cost is too high, and the population is dynamic in that the individuals making up the population may change over time. The three main advantages of sampling are that the cost is lower, data collection is faster, and since the data set is smaller it is possible to ensure homogeneity and to improve the accuracy and quality of the data. Each observation measures one or more properties (such as weight, location, color) of observable bodies distinguished as independent objects or individuals. In survey sampling, survey weights can be applied to the data to adjust for the sample design. Results from probability theory and statistical theory are employed to guide practice. In business and medical research, sampling is widely used for gathering information about a population (Ken Black, 2004). 2. Definition of terms

a) Population: According to Kothari C. (2004), a population is defined as all items in any field of inquiry while Olive M. Mugenda and Abel G. Mugenda (1999), defines the term population as the entire group of individuals, events or objects having a common observable characteristic. It can thus be said to mean a collection of all items which match given specification in a study. While many researches use a sample of the population for study, in some instances, a complete enumeration of all items in the population may be necessary. The process of undertaking a study in an entire population is known as census inquiry. Census is expensive in terms of time, money and energy hence...