To investigate cause and effect, you need to do a longitudinal study or an experimental study. Measure more than once. Some common approaches include textual analysis, thematic analysis, and discourse analysis. In research, you might have come across something called the hypothetico-deductive method. Construct validity. Both are important ethical considerations. There are seven threats to external validity: selection bias, history, experimenter effect, Hawthorne effect, testing effect, aptitude-treatment and situation effect. If you have a list of every member of the population and the ability to reach whichever members are selected, you can use simple random sampling. Do experiments always need a control group? It also has to be testable, which means you can support or refute it through scientific research methods (such as experiments, observations and statistical analysis of data). Whats the difference between exploratory and explanatory research? What is the difference between internal and external validity? Constructs exist at a higher level of abstraction than concepts. An error is any value (e.g., recorded weight) that doesnt reflect the true value (e.g., actual weight) of something thats being measured. Criterion validity and construct validity are both types of measurement validity. Its essential to know which is the cause the independent variable and which is the effect the dependent variable. Constructs can be conceptually defined in that they have meaning in theoretical terms. Next, the peer review process occurs. The clusters should ideally each be mini-representations of the population as a whole. Yes. Causation means that changes in one variable brings about changes in the other; there is a cause-and-effect relationship between variables. Whats the difference between a confounder and a mediator? In contrast, a mediator is the mechanism of a relationship between two variables: it explains the process by which they are related. A systematic review is secondary research because it uses existing research. You can organize the questions logically, with a clear progression from simple to complex, or randomly between respondents. In shorter scientific papers, where the aim is to report the findings of a specific study, you might simply describe what you did in a methods section. Conceptual research doesn't involve conducting any practical experiments. It is a tentative answer to your research question that has not yet been tested. Prevents carryover effects of learning and fatigue. Conceptual research is defined as a methodology wherein research is conducted by observing and analyzing already present information on a given topic. Its a non-experimental type of quantitative research. What is the difference between quota sampling and convenience sampling? Whats the difference between a mediator and a moderator? What is the difference between random sampling and convenience sampling? These actions are committed intentionally and can have serious consequences; research misconduct is not a simple mistake or a point of disagreement but a serious ethical failure. Attrition refers to participants leaving a study. What is the difference between a longitudinal study and a cross-sectional study? When should you use a structured interview? A semi-structured interview is a blend of structured and unstructured types of interviews. Quantitative methods allow you to systematically measure variables and test hypotheses. These principles include voluntary participation, informed consent, anonymity, confidentiality, potential for harm, and results communication. Uses more resources to recruit participants, administer sessions, cover costs, etc. What are the assumptions of the Pearson correlation coefficient? You can avoid systematic error through careful design of your sampling, data collection, and analysis procedures. Construct validity is often considered the overarching type of measurement validity. Concept - A concept is a generally accepted collection of meanings or characteristics that are concrete whereas a construct . To use a Likert scale in a survey, you present participants with Likert-type questions or statements, and a continuum of items, usually with 5 or 7 possible responses, to capture their degree of agreement. A confounding variable is closely related to both the independent and dependent variables in a study. The interviewer effect is a type of bias that emerges when a characteristic of an interviewer (race, age, gender identity, etc.) Data is then collected from as large a percentage as possible of this random subset. If the test fails to include parts of the construct, or irrelevant parts are included, the validity of the instrument is threatened, which brings your results into question. These types of erroneous conclusions can be practically significant with important consequences, because they lead to misplaced investments or missed opportunities. There are several methods you can use to decrease the impact of confounding variables on your research: restriction, matching, statistical control and randomization. Inductive reasoning is a method of drawing conclusions by going from the specific to the general. This type of validity is concerned with whether a measure seems relevant and appropriate for what its assessing only on the surface. Then, you can use a random number generator or a lottery method to randomly assign each number to a control or experimental group. What are independent and dependent variables? For strong internal validity, its usually best to include a control group if possible. Naturalistic observation is a qualitative research method where you record the behaviors of your research subjects in real world settings. It defines your overall approach and determines how you will collect and analyze data. Snowball sampling is a non-probability sampling method. Define and explain the difference between theory, concept, construct, variable, and model Theory: "a set of interrelated concepts, definitions, and propositions that presents a systematic view of events or situations by specifying relations among variables in order to explain and predict the events of the situations" The sign of the coefficient tells you the direction of the relationship: a positive value means the variables change together in the same direction, while a negative value means they change together in opposite directions. It is used in many different contexts by academics, governments, businesses, and other organizations. How do you define an observational study? There are three types of cluster sampling: single-stage, double-stage and multi-stage clustering. It is used by scientists to test specific predictions, called hypotheses, by calculating how likely it is that a pattern or relationship between variables could have arisen by chance. This Recall from Chapter 2 that constructs may be unidimensional (i.e., embody a single concept), such as weight or age, or multi-dimensional (i.e., embody multiple underlying concepts), such as personality or . What are the disadvantages of a cross-sectional study? Use more than one measure of a construct. In mixed methods research, you use both qualitative and quantitative data collection and analysis methods to answer your research question. is that concept is an understanding retained in the mind, from experience, reasoning and/or imagination; a generalization (generic, basic form), or abstraction (mental impression), of a particular set of instances or occurrences (specific, though different, recorded manifestations of the concept) while construct is something constructed from parts. A well-planned research design helps ensure that your methods match your research aims, that you collect high-quality data, and that you use the right kind of analysis to answer your questions, utilizing credible sources. How do you use deductive reasoning in research? It can help you increase your understanding of a given topic. Stratified and cluster sampling may look similar, but bear in mind that groups created in cluster sampling are heterogeneous, so the individual characteristics in the cluster vary. If you dont control relevant extraneous variables, they may influence the outcomes of your study, and you may not be able to demonstrate that your results are really an effect of your independent variable. For example, if you are interested in the effect of a diet on health, you can use multiple measures of health: blood sugar, blood pressure, weight, pulse, and many more. In order to collect detailed data on the population of the US, the Census Bureau officials randomly select 3.5 million households per year and use a variety of methods to convince them to fill out the survey. Qualitative data is collected and analyzed first, followed by quantitative data. Educators are able to simultaneously investigate an issue as they solve it, and the method is very iterative and flexible. Multistage sampling can simplify data collection when you have large, geographically spread samples, and you can obtain a probability sample without a complete sampling frame. Self-administered questionnaires can be delivered online or in paper-and-pen formats, in person or through mail. Data cleaning takes place between data collection and data analyses. What is the difference between confounding variables, independent variables and dependent variables? However, some experiments use a within-subjects design to test treatments without a control group. Experimental design means planning a set of procedures to investigate a relationship between variables. You can think of independent and dependent variables in terms of cause and effect: an. A regression analysis that supports your expectations strengthens your claim of construct validity. On the other hand, purposive sampling focuses on selecting participants possessing characteristics associated with the research study. Establish credibility by giving you a complete picture of the research problem. Whats the difference between questionnaires and surveys? Including mediators and moderators in your research helps you go beyond studying a simple relationship between two variables for a fuller picture of the real world. In this case, you multiply the numbers of subgroups for each characteristic to get the total number of groups. If you fail to account for them, you might over- or underestimate the causal relationship between your independent and dependent variables, or even find a causal relationship where none exists. The United Nations, the European Union, and many individual nations use peer review to evaluate grant applications. A construct refers to a concept or characteristic that can't be directly observed, but can be measured by observing other indicators that are associated with it. The difference between explanatory and response variables is simple: In a controlled experiment, all extraneous variables are held constant so that they cant influence the results. Random assignment is used in experiments with a between-groups or independent measures design. There are three key steps in systematic sampling: Systematic sampling is a probability sampling method where researchers select members of the population at a regular interval for example, by selecting every 15th person on a list of the population. Probability sampling methods include simple random sampling, systematic sampling, stratified sampling, and cluster sampling. Between-subjects and within-subjects designs can be combined in a single study when you have two or more independent variables (a factorial design). This means that each unit has an equal chance (i.e., equal probability) of being included in the sample. What are the pros and cons of a within-subjects design? The research methods you use depend on the type of data you need to answer your research question. Naturalistic observation is a valuable tool because of its flexibility, external validity, and suitability for topics that cant be studied in a lab setting. The main difference with a true experiment is that the groups are not randomly assigned. The purpose in both cases is to select a representative sample and/or to allow comparisons between subgroups. Whats the difference between action research and a case study? In statistics, sampling allows you to test a hypothesis about the characteristics of a population. What are the pros and cons of a between-subjects design? Both variables are on an interval or ratio, You expect a linear relationship between the two variables. These are the assumptions your data must meet if you want to use Pearsons r: Quantitative research designs can be divided into two main categories: Qualitative research designs tend to be more flexible. With this method, every member of the sample has a known or equal chance of being placed in a control group or an experimental group. A questionnaire is a data collection tool or instrument, while a survey is an overarching research method that involves collecting and analyzing data from people using questionnaires. Whats the difference between correlation and causation? Pearson product-moment correlation coefficient (Pearsons, population parameter and a sample statistic, Internet Archive and Premium Scholarly Publications content databases. 'A sentence may be constructed with a subject, verb and object.'; Concept noun. How can you ensure reproducibility and replicability? The external validity of a study is the extent to which you can generalize your findings to different groups of people, situations, and measures. An experimental group, also known as a treatment group, receives the treatment whose effect researchers wish to study, whereas a control group does not. Failing to account for confounding variables can cause you to wrongly estimate the relationship between your independent and dependent variables. What are the pros and cons of a longitudinal study? Some common types of sampling bias include self-selection bias, nonresponse bias, undercoverage bias, survivorship bias, pre-screening or advertising bias, and healthy user bias. What is the difference between purposive sampling and convenience sampling? When would it be appropriate to use a snowball sampling technique? Multiple independent variables may also be correlated with each other, so explanatory variables is a more appropriate term. It is important that the sampling frame is as complete as possible, so that your sample accurately reflects your population. After both analyses are complete, compare your results to draw overall conclusions. Phenomenology aims to explain experiences. Then, you take a broad scan of your data and search for patterns. No problem. Good face validity means that anyone who reviews your measure says that it seems to be measuring what its supposed to. You can use this design if you think the quantitative data will confirm or validate your qualitative findings. In your research design, its important to identify potential confounding variables and plan how you will reduce their impact. finishing places in a race), classifications (e.g. Constructs are conceptualized at the theoretical (abstract) plane, while variables are operationalized and measured at the empirical (observational) plane. An example of a proposition is: "An increase in student intelligence causes an increase in their academic achievement." The process of turning abstract concepts into measurable variables and indicators is called operationalization. How do explanatory variables differ from independent variables? Validity is the extent to which the scores actually represent the variable they are intended to. The main difference is that in stratified sampling, you draw a random sample from each subgroup (probability sampling). In a longer or more complex research project, such as a thesis or dissertation, you will probably include a methodology section, where you explain your approach to answering the research questions and cite relevant sources to support your choice of methods. The multistore model of human memory efficiently summarizes many important phenomena: the limited capacity and short retention time of information that is attended to but not rehearsed, the importance of rehearsing information for long-term retention, the serial-position effect, and so on. Common non-probability sampling methods include convenience sampling, voluntary response sampling, purposive sampling, snowball sampling, and quota sampling. Reliability and validity are both about how well a method measures something: If you are doing experimental research, you also have to consider the internal and external validity of your experiment. Unlike probability sampling (which involves some form of random selection), the initial individuals selected to be studied are the ones who recruit new participants. brands of cereal), and binary outcomes (e.g. Testing theories (i.e., theoretical propositions) require measuring these constructs accurately, correctly, and in a scientific manner, before the strength of their relationships can be tested. Blinding is important to reduce research bias (e.g., observer bias, demand characteristics) and ensure a studys internal validity. Structured interviews are best used when: More flexible interview options include semi-structured interviews, unstructured interviews, and focus groups. You need to know what type of variables you are working with to choose the right statistical test for your data and interpret your results. How do you plot explanatory and response variables on a graph? If participants know whether they are in a control or treatment group, they may adjust their behavior in ways that affect the outcome that researchers are trying to measure. Whats the difference between correlational and experimental research? Quasi-experimental design is most useful in situations where it would be unethical or impractical to run a true experiment. The findings of studies based on either convenience or purposive sampling can only be generalized to the (sub)population from which the sample is drawn, and not to the entire population. What is the difference between discrete and continuous variables? Our team helps students graduate by offering: Scribbr specializes in editing study-related documents. But triangulation can also pose problems: There are four main types of triangulation: Many academic fields use peer review, largely to determine whether a manuscript is suitable for publication. This includes rankings (e.g. Its a relatively intuitive, quick, and easy way to start checking whether a new measure seems useful at first glance. When should I use a quasi-experimental design? It's central to establishing the overall validity of a method. Thinking like a researcher implies the ability to move back and forth . 1.1 Concepts as mental representations. As shown in Figure 2.1, scientific research proceeds along two planes: a theoretical plane and an empirical plane. What is the difference between stratified and cluster sampling? Statistical analyses are often applied to test validity with data from your measures. This type of bias can also occur in observations if the participants know theyre being observed. Explanatory research is a research method used to investigate how or why something occurs when only a small amount of information is available pertaining to that topic. What are the main types of research design? a controlled experiment) always includes at least one control group that doesnt receive the experimental treatment. An observational study is a great choice for you if your research question is based purely on observations. In a between-subjects design, every participant experiences only one condition, and researchers assess group differences between participants in various conditions. Differential attrition occurs when attrition or dropout rates differ systematically between the intervention and the control group. A Likert scale is a rating scale that quantitatively assesses opinions, attitudes, or behaviors. Explain what a psychological construct is and give several examples. Unstructured interviews are best used when: The four most common types of interviews are: Deductive reasoning is commonly used in scientific research, and its especially associated with quantitative research. Inductive reasoning is also called inductive logic or bottom-up reasoning. There are eight threats to internal validity: history, maturation, instrumentation, testing, selection bias, regression to the mean, social interaction and attrition. The term explanatory variable is sometimes preferred over independent variable because, in real world contexts, independent variables are often influenced by other variables. How do you randomly assign participants to groups? Face validity and content validity are similar in that they both evaluate how suitable the content of a test is. For example, in an experiment about the effect of nutrients on crop growth: Defining your variables, and deciding how you will manipulate and measure them, is an important part of experimental design. What is the main purpose of action research? Each member of the population has an equal chance of being selected. While a between-subjects design has fewer threats to internal validity, it also requires more participants for high statistical power than a within-subjects design. You could also choose to look at the effect of exercise levels as well as diet, or even the additional effect of the two combined. A theory is a scientifically credible general principle that explains a phenomenon. Whats the difference between anonymity and confidentiality? It must be either the cause or the effect, not both! You are seeking descriptive data, and are ready to ask questions that will deepen and contextualize your initial thoughts and hypotheses. What are the benefits of collecting data? If you want to establish cause-and-effect relationships between, At least one dependent variable that can be precisely measured, How subjects will be assigned to treatment levels. A quasi-experiment is a type of research design that attempts to establish a cause-and-effect relationship. You are an experienced interviewer and have a very strong background in your research topic, since it is challenging to ask spontaneous, colloquial questions. Variables are properties or characteristics of the concept (e.g., performance at school), while indicators are ways of measuring or quantifying variables (e.g., yearly grade reports). What types of documents are usually peer-reviewed? Social desirability bias can be mitigated by ensuring participants feel at ease and comfortable sharing their views. Quantitative data is collected and analyzed first, followed by qualitative data. A true experiment (a.k.a. A measure with high construct validity accurately reflects the abstract concept that the researcher wants to study. 'structuralism is a difficult concept'; 'the concept of justice'; Without data cleaning, you could end up with a Type I or II error in your conclusion. You need to assess both in order to demonstrate construct validity. Dirty data contain inconsistencies or errors, but cleaning your data helps you minimize or resolve these. Methods are the specific tools and procedures you use to collect and analyze data (for example, experiments, surveys, and statistical tests). A concept is "an abstraction based on characteristics of perceived reality." Wow--that is pretty abstract itself. The directionality problem is when two variables correlate and might actually have a causal relationship, but its impossible to conclude which variable causes changes in the other. Constructs are abstract concepts specified at a high level of abstraction that are chosen specifically to explain the phenomenon of interest.
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