Research proposal (Lecture 3) Dr.Rehab F Gwada

Objectives of the Lecture The student at the end of this lecture should Know Identify Target Population and sample. Differentiate between Sample Selection Methods Determine Sample size Identify methodological section of research proposal.

Determination of the sample design The target population must be defined early in the survey- designing process. (population for which information is required). Target Population= the total group of interest Survey (sample) Population = the subgroup of the group of interest The goal of this process is to have the survey population as close as possible to the target population.(generalization) of conclusion

Determination of the sample design 1- A brief description of sample characteristics (sex, age, physical or mental status) 2-Choose the most appropriate survey time frame. 3-Define the place. 4-Establish the sample size (e.g., a sample of 100 from a population of 1,000). 5-Select a sampling method

Sample Selection Methods Simple Random Sample. - Convenience Sampling. Systematic Sample. - Purposive sampling Stratified Sampling. - Snowball sampling Cluster Sampling. - Quota sampling probability sampling non-probability sampling

Simple Random Sample In random sample,two criteria must be met: – 1-Every member of the population should have an equal probability of being included in the sample – 2-The choice of one member of the sample in no way should not affect the choice of another member in the sample. Eg.: Put all the name of the patients with the required criteria in a hat and pick out the number you need. The sample will be free from Bias (i.e. it's random!)

Systematic Sample With this method, items are chosen from the population according to a fixed rule(system), e.g. every 10thpatient along a list. This method should yield a more representative sample than the random sample (especially if the sample size is small). Example: Every other child with CP appearing in the clinic where the researcher is employed is selected for study.

Stratified Sampling The population is broken down into categories(strata), and a random sample is taken of each category. The proportions of the sample sizes are the same as the proportion of each category to the whole. Example: when we collect data on patients from several hospitals, we need adequate number of patients from each hospital

Cluster Sampling Used when populations can be broken down into many different categories, or clusters. Rather than taking a sample from each cluster, a random selection of clusters is chosen to represent the whole. Within each selected cluster, a random sample is taken.

Cluster Sampling Examples: Cluster sampling of the effect of a particular ex. Program on sixth-grade students. Obtain a cluster sampling by: – Choosing a particular region at random. – And using all students in the sixth-grade of a particular schools or schools as a sample.

Cluster Sampling Advantages: Less expensive and time consuming than a fully random sample. Can show "regional" variations. Disadvantages: Not a genuine random sample. Likely to yield a biased result (especially if only a few clusters are sampled).

Sample of convenience One of non-probability sampling The use of readily available subjects. Used more in health related research because of legal and ethical constraints. Once volunteers have consented to participate to study, they can be assigned randomly to different groups(control, experimental). It may introduce bias. It may not represent population. Example: using a sample of convenience of patients in certain diagnostic category at a single hospital.

Sample size This is the number of participants required for the sample. In practice, the sample size used in a study is determined based on: the expense of data collection the need to have sufficient statistical power.statistical power Usually large size samples are needed for relationship studies than are needed for comparative type studies.

Sample size there are different formulae of sample size calculations based on study designs, qualitative variable and quantities variables. (Charan and Biswas, 2013) Data from previous studies in the problem area can provide the researcher with some indication of how a large sample needs to produce significance results and to be generalized.

Research Proposal Sections of Research Proposal: proposal Title √ Introduction √ Literature Review √ Methodology

Methodology This section includes: Participants – Subjects' characteristics such as size, age, time & place of collection, inclusion and exclusion criteria. – Sampling methods  Instrumentation Outline the instruments you propose to use (surveys, scales, interview protocols, observation grids)or the sufficient details of any equipment will be used.

Methodology Procedures: The practical data collection process in some detail. Data analysis: The likely approach to data analysis requires clear description. Limitations of the study: These include any limitations in selecting a sample, using a measuring instrument, collecting data or analyzing results.

Research Proposal Delimitations : These refer to scope of the study by establishing limits of the study as : (1) number and kinds of subjects. (2) number and kinds of variables. (3) Instruments utilized. (4) Type of training program. (5) Time and duration of study. ( 6) Analytical procedure. Timetable. Budget: Financial support as costing photocopying, printing….etc

Methodology Ethical Issues: Consent form Informed and written, which is written in a clear, non-technical language. The researcher just mention in the participant section that the participants signed a written informed consent. Which ethics committee? eg. university, other

Question?