Introduction to Communications Research

Simple contain one independent and one dependent multivariate. . Testable the readiness to test the relationship among variables must be clear. 4. Useful should earmark current 3 criteria for monotheistic causal relationships 1 . Variables argon correlated I. E. Describes statistical relationship between 2 variables 2. The feat takes place before the marrow (post hoc ergo proper hoc) 3. The relationship between variables is non-spurious Monotheistic explanation is probabilistic in nature and is usually incomplete. Exceptions do not disprove a demonstrated monotheistic causal relationships. Causal relationships can exist unconstipated if they do not apply to the majority of cases.Longitudinal Studies Cross-sectional Studies Observations taken at single point in time. Explanation pass bys by examining differences crossways the units of compendium (hopefully representative of population). Less expensive, plainly harder to establish cause and effect. Observations are taken m ore than once. Explanation occurs by examining differences across time. More expensive, but easier to provide sense of cause and effect. Trend Studies Examines changes in a population across time. Investigator samples randomly from a population over time, with different individuals constituting severally sample. Hard to understand WHY change occurred as participants differ. cohort Studies A symbol of longitudinal research where an investigator randomly samples from a but cause and effect still hard to show as surveys change. Cohort outline Any try in which close to characteristic of one or more cohorts is measured at two or more times. Cohort a group of people who are linked by some common characteristic of life event. Panel Studies A longitudinal study that examines changes in individuals across time. Panel studies provide the opportunity for more in-depth analysis. distributively study collects data from he same individuals. Longitudinal panel studies are expensive but infor mative forms of research. One must account for scratch as each wave of data is collected from the panel. Reduce scratch by preparation and persistence.Disadvantages of Longitudinal Studies 1. By the time the study is complete, the pilot light measures entrust have become outmoded, and the overall social context will have changed. Critics will incredulity if the findings are relevant. 2. Longitudinal researchers have to harmonize postponed gratification. 3. Difficult to secure funding for longitudinal studies because funding iodides a great deal matter for measures relevant for cross-sectional questions, rather than longitudinal analysis. 4. Because of their expense, it will always be necessary to plan for multiple uses, and this carries the danger of not addressing any question thoroughly. 5. Attrition over time is an ever-present hazard.Advantages of Longitudinal Studies 1 . They resign an accurate time ordering of events to better address monotheistic causation. 2. They stand the study of within-individual change ? a more powerful causal analyses than cross-sectional surveys. 3. Because these are multiple data mints, they provide a better supplement on the handling of missing data Week 5 experimental invention 1 19th and 20th century classical experiment 0 Practice of holding everything constant except the one variable under consideration. 0 Not controlling all potential variables, but rather manipulating levels of selected independent variables in order to examine their influence on dependent variables.Control experimental design controls background variability so that positive effects of treatments can be observed. 1. Control by matching some sources of variation may be eliminated by matching, which limits inerrability However matching is further likely on known and observable characteristics and perfect matching is never possible 2. Control by randomization Converts of all irrelevant sources of possible systematic variability into unsys tematic variability (random error) Like life insurance, a precaution against disturbances that may or may not occur and that may or may not be serious if they do occur 3. Control by statistical adjustment Uses statistical relations to take matching and increase clearcutness.Week 6 Experimental Design 2 Design Total experimental plan or structure of experimental research. Pre-test The initial observation of DVD among subjects (prior to V). Post-test The measurement of DVD among subjects (after introduction of V). Laboratory Experiments vs. theatre of operations Experiments Ecological validity Hawthorne Effect where subjects alter their behavior because they know they are being studied. As such, field experiments are often non-reactive. But often results in lack of control, as intervening variables might affect the precision of the experiment. Pre-experiments designs follow basic experimental steps but fail to take a control group or random assignment. One-Shot Case athletic fiel d One-Group Pre-Test-Post-Test Design