population - the totality of all the objects, elements, persons, and characteristics under consideration
population - it is understood that this population possesses common characteristics about which the research aims to explore
two types of population
target population
accessible population
actual population - the target population
accessible population - the portion of the population in which the researcher has reasonable access
sample - when the population is too costly or time-consuming or impractical to consider, a representative is identified
sampling - pertains to the systematic process of selecting the group to be analyzed in the research study
sample - the goal is to get information from a group that represents the target population
a good sample should have characteristics of the represented population- characteristics that are within the scope of the study with fair accuracy
approaches in identifying the sample size:
heuristics
literaturereview
formulas
poweranalysis
heuristics - this approach refers to the rule of thumb for sample size
research design [no.of subjects/participants]
descriptive - 10% to 20%
comparative research - 15subjects/ groups
survey- 800
correlational- 100-200
ex post facto - 30+
experimental - 30/more
literature review - this approach is by reading similar/ related literature and studies to your current research study. Using this approach increases the validity of your sampling procedure.
formulas - being established for the computation of an acceptable sample size. The common one is Slovin's Formula.
Slovin's Formula - n=N/1+Ne^2
power analysis - this approach is founded on the principle of power analysis. There are two principles you need to consider if you are going to use this approach: statistical power and effectsize.
statistical power - the probability of rejecting the null hypothesis.
statistical power - it suggest that there is a relationship between the independent and dependent variables of the research study.
statistical power - It will be used to identify the sufficient sample size for measuring the effect size of a certain treatment.
effect size - the level of difference between the experimental group and the control group
if the statistical power tells that relationship between independent and dependent variables, the effect size suggests the extent of the relationship between these two variables.
once a good sample is obtained, the generalizability and applicability of findings increase