Sampling Techniques

Sampling is the act, process or technique of selecting a suitable sample or a representative part of a population for determining parameters or characteristics of the whole population (Kombo and Tromp, 2006:52). Statistical sampling techniques are the strategies applied by researchers during the statistical sampling process. This process is done when the researchers aims to draw conclusions for the entire population after conducting a study on a sample taken from the same population. Representativeness is the primary concern in statistical sampling (Castillo, 2009:5). The sample obtained from the population must be representative of the same population to enable generalization of the study findings.

The researcher received a list of Primary Schools from each Sub-county Quality Assurance and Standard Officer (Sub-County QASO) in each of the districts sampled for the study. The researcher with the help of socio-economic information regarding schools from the education office, stratified schools and then random sampled three schools according to socio-economic considerations of the schools such as amount of levies charged by the schools and other considerations as guided by respective Educational Officers to enable the study to achieve its objectives.

All public primary schools were stratified based on socio-economic status. In probability samples, each member of the population has a known non-zero probability of being selected; that is each member of population has equal chance of being selected for the study (Castillo, 2009:5). Stratification is the process of grouping members of the population into relatively homogeneous subgroups before sampling (Johnson and Christensen, 2008:80). A stratified sample is a probability sampling technique in which the researcher divides the entire target population into different subgroups, or strata, and then randomly selects the final subjects proportionally from the different strata (Castillo, 2009:6). A method of sampling that involves the division of a population into smaller groups known as strata. In stratified random sampling, the strata are formed based on members' shared attributes or characteristics such as socio-economic status among many others (Black, 1999:118). A random sample from each stratum is taken in a number proportional to the stratum's size when compared to the population. These subsets of the strata are then pooled to form a random sample for the study (Cochran 1997:28). This technique enabled the researcher to capture key population characteristics in the sample according to socio-economic status and their implications to NCLSDs that the study explored.

Applied in this study, a stratified sampling of the schools was done according to socio-economic status. The schools were stratified and categorised as HSES, MSES or LSES. The schools were stratified as shown in the Figure 3.1, subsequently; from each stratum, one school was randomly sampled.

Figure 3.1. Sampling frame showing Stratified Sampling of the Schools according to SES

Source: Sampling Frame

The Figure 3.1 shows the three schools that were sampled according to SES. The sampling frame shows that each of the three major socio- economic statuses in Kenyan society were represented in the sample. This enabled the study to be more representative of the Kenyan society and in particular capture various SES and their lifestyle patterns. This was done by including schools that had pupils from various socio- economic backgrounds to enable the researcher to make comparisons and contrasts between various socio-economic groups in society and their implications for NCLSDs. It also enabled the study to establish if socio-economic status had any role in predisposing pupils to NCLSDs. Moreover, the three schools were from different districts, for example, in Westland Sub-county, Bonoko Primary School (BPS) was selected to represent high socio-economic status (HSES). According to information from City Educational Officers in-charge of these schools, BPS enrolled pupils who were mainly drawn from a HSEs catchment area where it is located. This enabled the researcher to explore the contributions of HE to lifestyles among pupils from HSES. In Kamukunji Sub-county, Msemayote Primary School (MPS) was selected to represent middle socio-economic status (MSES) since the pupils who attend the school are drawn mainly from Uhuru Estate, which is owned mainly by civil servants. The school enabled the researcher to capture culture and lifestyle of pupils from middle class that enabled the study to explore the role of HE in promoting healthy lifestyles to prevent NCLSDs.

In Embakasi Sub-county, JPS (JPS) that has catchments from slums in Korogocho, Kiambio and Mukuru were selected to represent Low socio- economic status (LSES). The school enabled the researcher to capture various practice and lifestyles of pupils from LSES and how HE enabled them to promote HL to prevent NCLSDs. Choice of three schools from

Public Primary Schools in Nairobi County

MSES LSES HSES One school One school One school

different socio-economic status enabled the researcher to make comparisons from three different socio-economic backgrounds, which make the finding reliable.

The schools sampled for the study were Public Primary Schools because they are the ones that use the government-KIE curriculum that has HE, offer FPE and because they enrol pupils from their immediate environment. Public schools also apply and follow educational policies from the government which include KSHP and other health guidelines. This was critical for the study because it enabled the study to capture the variables envisaged in the study through a cross-section of the society hence making the findings valid and reliable. The urban location of the Sub-county and accessibility of the schools made it suitable for the study to explore the role of HE in schools exposed to changes in lifestyles in city environment with concomitant modernization and urbanization that have great impact or emerging lifestyles in society, which may predispose pupils to NCLSDs. Further, only public schools were selected for study because previous attempts to study social behaviour in private schools had been met with resistance and hostility by administrators who fear negative labelling of their schools (Kombo, 1998:24). Being commercial institutions, adverse publicity could perhaps translate into fewer enrolments hence less income. Moreover, private Primary schools were not involved in the study since most of them offered curriculum that did not necessarily have HE and also the feeling that the administration in most of them may be uncooperative due to fear that the study may reveal issues that may adversely affect their reputation and enrolment; further, Private Schools may have personnel who might have gone through international curriculum and training which may not had HE, hence, not useful for the study.

In all the schools sampled, school administration did not allow Standard Eight pupils to be involved in the study because the schools had set strict schedules to prepare them for national examinations. The school administrators told the researcher and his assistants that PTA’s and education officers had resolved in their annual general meetings that Standard Eight pupils should be kept busy without and outdoor or external involvements so that the school can improve performance in examinations. They further said that ‘Standard Eight being the final year in school where candidates were to do a first and final national in primary education required a lot of sacrifices to be made to ensure nothing interferes with KCPE which is the first critical examination in pupils’ life’; hence, pupils in Standard Eight were always kept busy in class by their teachers to ensure they were adequately prepared.

The researcher was allowed to sample other classes in the school except Standard Eight. In each of the schools sampled for the study,

purposive sampling was used to select Standard Seven pupils for the study. The logic of purposive sampling of Standard Seven was premised on the fact that apart from Standard Eight pupils who were candidates for national examinations who could not be sampled due to strict time schedules that schools had set to prepare them for national examinations, Standard Seven pupils were more exposed to HE compared to other pupils in the school based syllabus coverage, age and time spent in school which may have exposed them more to lifestyles due through formal socialization using formal curriculum and informal socialization through social interaction with other pupils, teachers and other socializers in the school fraternity.

Purposively sampling is a non-probability method where the researcher purposely targets a group of people believed to be reliable for the study to provide answers to research questions (Kombo and Tromp, 2006:56). Purposive sampling is a common non-probability method where the researcher selects the sample based on judgment, which is based on the objectives of the study (Black, 1999:24). In this study, the researcher purposively sampled Standard Seven pupils since it was representative of other pupils in the schools because it had boys and girls who had been in school the longest apart from Standard Eight, which was examination class which could not be sampled due to ethical reasons. The Standard Seven pupils had all the elements that could capture issues raised in the study objectives, which made the sample relevant and appropriate for this study. Applied in this study, purposive sampling enabled the researcher to select Standard Seven informants who due to being in school longer compared to other pupils had been exposed more to formal and informal socialization patterns in the schools which enabled the study to capture the contributions of HE to lifestyles.

The study used purposive sampling technique to select individual pupils to be involved in the study. In this case, purposive sampling involved selecting study informants from a list of cases by picking cases as determined by the researcher (Black, 1999:22). In this study, the researcher used a strict criterion so as to capture lifestyle and social behaviour patterns that could enable the study to capture the actual contributions of HE. The main criterion for the inclusion of the pupils into the sampling frame was the leadership nature of the pupils determined through the construction of a sociometric matrix of best friends from the class. Sociometry is concerned with the social interactions among any group of people like peer groups and cliques among pupils. The researcher and his assistants received information from other pupils and teachers that made selection of the pupils involved in the study quite objective. Sociometry is the systematic study of social interactions and social preferences among a group of people who share and interact in a common social environment (Black, 1999:24; Kidder, 1981:89). Sociometry identifies friendship and

work/play relationships preferences within a group (Muia, 2001:83). The rationale for using sociometry in this study was to enable the study to capture social groups that pupils identified themselves with so as to explore their social relationships and how they influenced each other as well as the results of group influences in lifestyles. This enabled the study to capture valuable information regarding lifestyles and how they related to feeding habits, play and physical exercises, which had implications to their health.

In this study, leadership was not explainable by any particular personality characteristic or constellation of traits (Kiddler, 1981:192). It was rather determined because of the interpersonal contribution of an individual in a specific group. Key informants are essentially individual pupils or a selected group who are in a position to provide the needed information, ideas and insights (Kumar, 1993:13). The body of pupils in any school is constituted by small subgroups and cleavages based on pupils interests. Each of the networks of these relationships has leaders. Hence, the choice of leaders through the sociometry nomination method to serve as key informants for the study was critical since leaders exercised great influences in various groups of pupils. This enabled the study to capture issues relating to lifestyles and influence of peers to particular tastes, values, inclinations, stereotypes, preferences and resultant lifestyles that would enable the study to achieve its objectives.

Applied in this study, peer influences in various group leaderships, feeding lifestyles and feeding habits were important relationships since they influence attitudes, feelings, beliefs and perceptions of members towards certain lifestyles that could predispose them to NCLSDs. This approach was quintessential in this study to establish the role of HE on healthy lifestyles of pupils since peer leaders used their influence and popularity to shape beliefs, habits and practices that informed peer influence on various lifestyles that were observable among pupils in certain classes; these influences determined the type of lifestyle adopted by other pupils which included language use like ‘sheng’, dressing codes, eating habits, games played and patterns/types of exercises. Peer leaders also exercised greater influence on social interaction and beliefs, views and perceptions of other pupils in the clique, which predisposed them to lifestyles that veered to NCLSDs; hence, it was critical that the study selected them as key informants of the study.

Key informants were essentially individual pupils or a selected group who were in a position to provide the needed information, ideas and insights (Kumar, 1993:13). The pupils who were selected were popular leaders of their groups of friends; therefore, they were considered qualified to be key informants since they influenced action competence in HE behaviour and habits of fellow pupils; hence, crucial for this

study. In each of the three schools sampled, all the pupils in Standard Seven were provided with pieces of paper and requested to write the names of their best friends in their class. The researcher then collected the papers and carefully analysed them to establish the most popular pupils who were had the highest frequency. After establishing the popular leaders among each gender, two sociograms were developed, one for boys and another one for girls. This was done, because ordinarily, observations reveal that girls and boys may tend to stay and associate in gender-segregated groups (Muia, 2001:89).

The lists of friends were sorted into two files, one for boys and one for girls. The development of a sociometric diagram started by writing the names of the popular pupils on a large piece of paper; more names were added and arrows drawn progressively showing the choice of friends depending on the popularity. At the end, a cluster of friends emerged. The pupils at the centre of the clusters were selected as key informants for the FGDs and unstructured interviews. The names of the informants were replaced with numbers due to ethical considerations. The diagrammatic representations of the sociograms were as illustrated in Figure 3.2.

Figure 3.2. Diagrammatic Representation of The Sociometric Diagram Showing the Sampling Process Used to Select the Sample of Pupil’s Informants for the Study

Key

Numerical numbers are randomized for the sake of identity of the cluster.

The key informants will be identified by being in the centre of a cluster of friends in a rectangle

An arrow stands for the choice of a friend.

More arrows show that one has more friends hence more popular and perhaps influential in a group which made him/her to be selected for FGD because of the leadership role in the group; this implied that the persons selected were likely to exercise influence opinions/views/attitudes/beliefs about lifestyle patterns susceptible to practices that may predispose fellow pupils to practices that could predispose them to NCLSDs, hence very resourceful for this study.

The preceding sociometric process was done for boys and girls study informants separately to ensure gender parity. The overall sample size and the composition was determined as the fieldwork progressed. This strategy was because in qualitative study sample size depends on the purpose of inquiry, what is at stake, what will be useful, what will have credibility and what could be done with available time and resources (Patton, 1990:92). Gender parity was maintained in all the samples by selecting equal number of each gender to participate in the study so as to make the sample fairly representative (Kombo and Tromp, 2006:82). 3.5.1 Sample Size

Stratified random sampling was used to select schools that were sampled for the study. The schools were stratified according to their socio-economic status and then random sampled for the study. This ensured that each specific group was represented in the sample which was drawn from each stratum. A stratum is a subset of the population that share at least one common characteristic (Black, 1999:24; Castillo, 2011:12). In this study it was based on the type of socio-

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economic class; that is either belonging to HSES, MSES or LSES. The schools were stratified and random sampled and sample size was as shown in Table 3.1.

Table 3.1 Type and number of schools sampled in their respective categories of SES

Type of School Sub-county Number of Schools

selected Pseudo name for the School

High SES – Public Westlands 1 Bonoko

Middle SES -

Public Kamukunji 1 Msemayote

Low SES – Public Embakasi 1 Jitetee

Total sample 3 Sub-

counties

3 schools 3 Pseudo names for

schools Source: Sampling frame

Table 3.1 shows the product of sampling process that was used to sample three schools for the study. The findings show that Bonoko Primary School in Westlands Sub-county was sampled to represent HSES; Msemayote Primary School in Kamukunji Sub-county was sampled to represent MSES while Jitetee Primary School in Embakasi Sub-county was selected to represent LSES. The schools were sampled to represent each socio-economic class to enable the findings of the study to be representative. The researcher further ensured the schools were from different districts of Nairobi County to ensure fair representation of characteristics of pupils in public schools to enhance reliability of the study findings. The entire report has adopted pseudonyms for schools and all informants due to ethical reasons to enhance confidentiality. A list of Pseudonyms is provided in the Appendix IV. Any semblance with known persons and places is purely coincidental. Data on enrolment was captured using Appendix III. The total sample for the study was 177 informants.