Sampling Techniques in Research PDF

**SAMPLING** Formal *process of choosing the correct subgroup* called a **sample** from a population to participate in a research study. **TWO KINDS OF SAMPLING PROCEDURES** 1. Probability Sampling Technique 1. Non-Probability Sampling Technique **Probability Sampling Technique** 1. *Each s...

**SAMPLING** Formal *process of choosing the correct subgroup* called a **sample** from a population to participate in a research study. **TWO KINDS OF SAMPLING PROCEDURES** 1. Probability Sampling Technique 1. Non-Probability Sampling Technique **Probability Sampling Technique** 1. *Each sample or element from the population has on* **equal chance of selection** under a given sampling technique. **What are the kinds of probability sampling techniques used in a research?** 1. SIMPLE RANDOM SAMPLING 2. STRATIFIED SAMPLING SIMPLE 3. CLUSTER RANDOM SAMPLING 4. SYSTEMATIC RANDOM SAMPLING **PROBABILITY SAMPLING TECHNIQUE** 1. Simple Random Sampling - **[Most frequently/commonly]** used type of probability sampling technique. *This is characterized by the idea that the [chance of selection is the same] for [every member of the population.]* 2. Cluster Sampling - Stratified Random sampling *also [gives an equal chance] to all members of the [population to be chosen]*. - Population is *first divided into* **[strata or groups]** before *selecting the samples.* 3. Sample Size per Subgroups - Usually applied in **[large-scale studies,]** *[geographical spread out of the population] is a "[challenge"]*, and gathering information will be very time-consuming. 4. Systematic Sampling - Simple as selecting samples **[every nth]** (example every 2^nd^, 5^th^) of the *chosen population [until arriving at a desired total number of sample size.]* - Selection is based on a **[predetermined interval]**. Dividing the *population size* by the *sample size*, the interval will be obtained. **Non-probability Sampling Procedures** - May be used when the **[researcher cannot employ random selection. ]** **What are the kinds of non-probability sampling techniques used in a research?** - **Convenience Sampling**: - The researcher **selects** **participants who are "readily available".** - Selecting samples that are [available] and [are capable of participating] in a research study on a current issue. - **Easy way out** (Choosing your family as the respondent) 2. **Snowball Sampling**: - The researcher identifies a few **initial participants** and then asks them to **[refer] other potential participants.** - Researchers identifies a key informant about a research of interest and then ask that respondent to refer or identify another respondent who can participate in the study. - **Pass the message** ([Participants recommending] or giving another [respondent]) 3. **Purposive Sampling**: - **The researcher selects participants based on specific criteria**. - Also called **subjective sampling**. It employs a procedure in which [*samples* are chosen for a *special purpose*]. - **Highly specific** (choosing [STEM Students] as your "Respondents") 4. **Quota Sampling**: - The researcher [sets **quotas**] for different categories of participants and then [selects **participants** to meet those quotas.] - Gathering a **[representative sample from a group]** based on [certain characteristics] of the population chosen by the researcher. - **One for all** (selecting [one resident] as a respondent per Barangay in Santa Maria) **RESEARCH INSTRUMENT , VALIDITY AND REALIBILITY** **DATA COLLECTION** - Process by which the **researcher collects the information** *needed to [answer the research problem].* - In research is a form of evidence. It **justifies** *how researchers reach a decision* (conclusion). **RESEARCH INSTRUMENTS** - **Basic tools** researchers *used to gather data* for specific research problems. - Common instruments are performance tests , questionnaires , interviews , and observation checklist. - The type of instrument , reasons for choosing the type , and the description and conceptual definition of its parts are some of the factors that need to be decided before constructing a research instrument. **CHARACTERISTICS OF A GOOD RESEARCH INSTRUMENTS** 1. Concise 2. Sequential 3. Valid and Reliable 4. Easy Tabulated **WAYS IN DEVELOPING RESEARCH INSTRUMENTS** There are three ways you can consider in developing the research instrument for your study. 1. **Adopting instrument from the already utilized** instruments from previous related studies. 2. **Modifying an existing instrument when the available instruments do not yield the exact data** that will answer the research problem. 3. When the researcher **made his own instrument that corresponds to the variable and scope** of his current study. **COMMON SCALES USED IN QUANTITATIVE RESEARCH** **LIKERT SCALE** Also called **subjective sampling**. It employs a procedure in which samples are chosen for a special purpose. *Most common scale used in [quantitative research ]*. Respondents were asked to r**ate or rank statements according to the scale provided**. FREQUENCY OF OCCURRENCE - Very Frequently - Frequently - Occasionally - Rarely - Very Rarely FREQUENCY OF USE - Always - Often - Sometimes - Rarely - Never **Closed questions or multiple** -- choice questions may also be used in a quantitative research. These questions may **consist of three or more mutually exclusive questions with different categories**. **Rank** -- order scale questions are used when **respondents are asked to rank their choices on each statement or item**. *Ranking requires that a set of items be **ranked in order*** to compare each item to all others. **SEMANTIC DIFFERENTIAL** A series of **bipolar adjectives** will be rated by the respondents. This scale seems to be more advantageous since it is more flexible and easy to construct. - Scale from 5-1 (5 -- Pleasant to 1- Unpleasant ) - \[Choose in between or between numbers\] **CHARACTERISTICS OF A GOOD QUESTIONNAIRE** 1. Make sure that the question **statement is expressed in a concise manner**. 2. The terms or **words used are easy to understand** , simple and explained properly. 3. The questions or **statements are arranged properly in a logical manner** and categorized accordingly. 4. **Avoid the use of double negatives** or more than one negative word in the question or statement. 5. Make sure that statements or **questions are expressed correctly and is grammatically correct**. **ESTABLISHING THE VALIDITY OF THE QUESTIONNAIRE** A questionnaire undergoes a validation procedure to make sure that *[it accurately measures what it aims to do]*. **A valid questionnaire helps to collect reliable and accurate data**. **VALIDITY** - A research instrument is considered valid if it **measures what it supposed to measure**. **RELIABILITY** - Refers to the **consistency of the measures** or result of the instrument **WAYS TO ASSESS VALIDITY** 1. Face Validity 2. Content Validity 3. Construct Validity 4. Concurrent Validity 5. Predictive validity **Face Validity** - It is also known as " ***logical validity*** " It calls for an initiative judgment of the instruments as it " appear ". **Just by looking at the instrument , the researcher decides if it is valid**. **Content Validity** - An instrument that is **judged with content validity meets the objectives of the study**. It is done by [checking the statements or questions if this elicits the needed information]. **Construct Validity** - It refers to the validity of **instruments as it corresponds to the theoretical construct of the study**. It is concerning if a [specific measure relates]. **Concurrent Validity** - When the instrument can **predict results similar to those similar tests already validated** , it has concurrent validity. **Predictive Validity** - When the **instrument is able to produce results similar to those similar tests** *that will be employed in the* **[future]** , it has predictive validity. **REABILITY OF INSTRUMENT** 1. Test -- retest Reliability 2. Equivalent Forms Reliability 3. Internal Consistency Reliability **Test -- retest Reliability** - it is achieved by giving the same test to the same group of respondents twice. The consistency of the two scores will be checked. **Equivalent Forms Reliability** - Administering two identical tests except for wordings to the same group of respondents. **Internal Consistency Reliability** - Determines how well the items measure the same construct. There are three ways to measure the internal consistency : - Split -- Half - Coefficient Cronbach's - Alpha Kuder -- Richardson Formula **THREATS** - FACTORS THAT COMPROMISE THE VALIDITY OF A RESEARCH STUDY. **THREATS TO INTERNAL AND EXTERNAL VALIDITY** - Is the researcher's conclusion correct ? - Are the changes in the independent variable indeed responsible for the observed variation in the dependent variable ? - Is it possible that the variation in the dependent variable can be attributed to other factors ? **WHY IS INTERNAL VALIDITY IMPORTANT ?** - If the study shows a high degree of internal validity , then we can conclude that we have strong evidence of causality. - If a study has low internal validity , then we can conclude that the study has little or no evidence of causality. **THREATS TO INTERNAL VALIDITY** 1. **HISTORY** Refers to any event outside of the research study that can alter or effect subjects ' performance. **2. MATURATION** Refers to the natural physiological or psychological changes that take place as we age. **3.MEASURING INSTURMENTS** Changes in instruments , calibration of instruments , observers , or scorers may cause changes in the measurements. 4. **STATISTICAL REGRESSION** refers to the tendency for subjects who score very high or very low to score more toward the mean on subsequent testing. 5. **EXPERIMENTAL MORTALITY** The loss of subjects from comparison groups could greatly affect the comparisons because of unique characteristics of those subjects. Groups to be compared need to be the same after as before the experiment. **EXTERNAL VALIDITY** - Refers to the generalizability of a study. Asks to what populations , settings , treatment variables , measurement variables can this observed effect be generalized. **THREATS TO EXTERNAL VALIDITY** 1. **PRE -- TESTING** Individuals who were pretested might be less or more sensitive to the experimental variable or might have " learned " from the pre -- test making them unrepresentative of the population who had not been pre -- tested. 2. **DIFFERENTIAL SELECTION** The selection of the subjects determines how the findings can be generalized. Subjects selected from a small group or one with particular characteristics would limit generalizability. Randomly chosen subjects from the entire population could be generalized to the entire population. 3. **EXPERIMENTAL PROCEDURES** 1. **Write the Background Information** - It is an introductory paragraph that explains the relevance of the intervention to the study conducted. It also includes the context and duration of the treatment. 2. **Describe the Differences and Similarities between the Experimental and Control Group** - State what will happen and what will not both in the experimental and control groups. This will clearly illustrate the parameters of the research - In particular , describe how will the experimental group receive or experience the condition. It includes how will the intervention happens to achieve the desired result of the study. For example , how will the special tutorial program will take place ? 4. **Explain the Basis of Procedures** - The reason for choosing the intervention and process should clear and concrete reasons. The researcher explains why the procedures are necessary. In addition , the theoretical and conceptual basis for choosing the procedures is presented to establish the validity of the procedures. **PLANNING DATA COLLECTION PROCEDURE TECHNIQUES IN COLLECTION QUANTITATIVE DATA :** 1\. OBSERVATION 2\. SURVEY 3\. EXPERIEMENT **DATA ANALYSIS** A process in which gathered information are summarized in such a manner that it will yield answers to the research questions. **PLANNING DATA ANALYSIS** **TYPES OF STATISTICAL ANALYSIS** 1. **Descriptive Statistical Technique** - Provides a summary of the ordered or sequenced data from your research sample. Frequency distribution , measure of central tendencies ( mean , median , mode ) , and standard deviation are the sets of data from descriptive statistics. 2. **Inferential Statistics** - Used when the research study focuses on finding predictions ; testing hypothesis ; and finding interpretations , generalizations , and conclusions. Since this statistical method is **more complex and has more advanced mathematical computations** , you can use computer software to aid your analysis. A univariate analysis means analysis of one variable. Analysis of two variables such as independent and dependent variables refers to bivariate analysis while the multivariate analysis involves analysis of the multiple relations between multiple variables. **STATISTICAL TECHNIQUES IN QUANTITATIVE RESEARCH** **Test of Relationship between Two Variables** - Pearson's r ( parametric ) - Phi coefficient ( non -- parametric for nominal and Dichotomous variables) - Spearman's rho ( non -- parametric for ordinal variable) **Test of Difference between Two Data Sets from One Group** - T -- test for dependent samples ( parametric ) - McNemar change test ( non -- parametric for nominal and dichotomous variables ) - Wilcoxon signed -- rank test ( non -- parametric for ordinul variable ) **Test of Difference between Two Data Sets from Two Different Groups** - test for independent samples ( parametric ) - Two -- way chi -- square ( non -- parametric for nominal variable ) - Mann -- Whitney U test ( non -- parametric for ordinal variable ) **Test More than Two Population Means** - Analysis of Variance or ANOVA ( parametric ) **Test the Strength of Relation or Effect or Impact** - Regression ( parametric ) **DATA COLLECTION , PRESENTATION , AND ANALYSIS** **DATA COLLECTION INSTRUMENTS** Data Collection - Obtaining relevant information regarding the specified research questions or objectives. - In collecting the data , the researcher must decide on the following questions : When developing and utilizing a research instrument , the following steps are to be considered. 1. Be clear with your research question. 2. Plan how you will conduct the data collection. 3. Use appropriate research instruments. 4. Collect , tabulate , tally , and analyze the data. 5. Verify the validity and reliability of the collected data. 6. Present your findings. **DATA PRESENTATION AND INTERPRETATION ( USING TEXT , TABLE AND GRAPHS )** To be able to create and present an organized picture of information from a research report , it is important to use certain techniques to communicate findings and interpretations of research studies into visual forms. The common techniques used to display data results are textual , tabular and graphical. **TEXTUAL PRESENTATION OF DATA** Use words , statements or paragraphs with numerals , numbers or measurement to describe data. It can be used independently to describe the data when there are very few quantities or numbers. It should include the following parts : 1\. Table number and title ( placed above the table ) 2\. Caption subhead ( columns and rows ) 3\. Body ( contains all data ) 4\. Source ( Optional. Used if the data is secondary ) **GRAPHICAL METHODS OF PRESENTING DATA** **GRAPHS** A **graph** or **chart** *[portrays the visual presentation of data]* using symbols such as lines , dots , dots or slices. It depicts the trend of a certain set of measurements or shows comparison between two or more sets of data or quantities. **Graphs focuses on how a change in one variable relates to another**. Graphs use bars , lines , circles , and pictures in representing the data. - **Line Graph** illustrates *trends and changes in data over time* - **Bar Graph** illustrates *comparisons of amounts and quantities ,* - while **Pie Graph** ( Circle Graph ) *displays the relationship of parts to a whole.* **USING STATISTICAL TECHNIQUES ΤΟ ANALYZE DATA** - Percentage , Mean , Standard Deviation , Correlation , Regression , and Hypothesis Testing. **PURPOSES OF A RECOMMENDATION** **PRESENTATION OF FINDINGS AND INFORMATION CONCLUSION AND RECOMMENDATION** 1. **POLICY RECOMMENDATION -** Serve to inform people who are faced with policy choices on particular issues about how research and evidence can help to make the best decisions. It is about using research to solve a public policy problem or to provide evidence about how a policy is working. 3. **TO SOLVE PROBLEMS DISCOVERED IN THE RESEARCH STUDY -** Encountered problems while doing the research study that needs to be resolved. **CONCLUSION** - It represents inferences drawn from the findings of the study. The number of conclusions coincides with the number of specific findings. If there are tested hypotheses in the study , the rejections or acceptance of hypotheses are placed under conclusion. **RECOMMENDATION** - Are suggestions / solutions that address certain problems based on your study results. **STRATEGIES FOR WRITING EFFECTIVE CONCLUSIONS** 1\. Conclusions are intertwined or link together with the Introduction 2\. Conclusions are inferences and generalizations based upon the findings 3\. Conclusions should specifically answer the questions posed in the Statement of the Problem 4\. Conclusions should contain facts or actual results from the research study