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  • 1. SAGE Research MethodsAboutWhats New?TutorialsHelpHow To PurchaseUser Resourceso Librarian Resourceso Faculty Resourceso Web ResourcesMember Sign in Not a Member? Sign up for save and search tools.Search:BrowseContento All Contento Bookso Dictionarieso Encyclopediaso Journal Articleso Little Green Bookso Little Blue Bookso VideosAuthors & EditorsMethods MapMethods Listso My Methods Listso All Methods ListsVideosShareText sizeiconEncyclopediaAdd to Methods ListFind in printView full screen
  • 2. Encyclopedia of Survey Research MethodsPaul J. LavrakasPub.date: | DOI: 10.4135/9781412963947Print ISBN: 9781412918084 | Online ISBN: 9781412963947Encyclopedia EntrySolomon Four-Group DesignM. H. Clark & William R. ShadishThe Solomon four-group design is an experimental design that assesses the plausibility of pretestsensitization effects , that is, whether the mere act of taking a pretest influences scores onsubsequent administrations of the test. For example, if respondents complete a questionnairemeasuring their knowledge of science as a pretest, they might then decide to subsequently seekanswers to a few unfamiliar equations. At the posttest they might then score better on the sciencetest compared to how they would have scored without taking the pretest. Meta-analytic resultssuggest that pretest sensitization does occur, although it is more prevalent for some measuresthan others, and the more time passes between pretest and posttest, the less likely a testing effectwill occur. In the Solomon four-group design, the researcher randomly assigns respondents toone of four cells constructed from two fully crossed factors: treatment (e.g. treatment andcontrol) and pretest administration ...Users without a subscription are not able to see the full content on this page. Please, subscribe orlogin to access all Methods content.Click here to see full textBook Info PageAbout this titleTable of contentso Front Mattero A ABC News/Washington Post Poll Access Lines Acquiescence Response Bias Adaptive Sampling Add-a-Digit Sampling Address-Based Sampling
  • 3.  Advance Contact Advance Letter Agenda Setting Aided Recall Aided Recognition Algorithm Alpha, Significance Level of Test Alternative Hypothesis American Association for Public Opinion Research (AAPOR) American Community Survey (ACS) American Statistical Association Section on Survey ResearchMethods (ASA-SRMS) Analysis of Variance (ANOVA) Anonymity Answering Machine Messages Approval Ratings Area Frame Area Probability Sample Attenuation Attitude Measurement Attitudes Attitude Strength Attrition Audio Computer-Assisted Self-Interviewing (ACASI) Aural Communication Auxiliary Variable Abandoned Calls Absolute Agreement Absolute Frequency Accuracy Action Research Active Listening Skills Active Screening Adding Random Noise Address Matching Adjustment Errors Agree-Disagree Scale Analysis Unit Ascription Asymptotically Design Unbiased Attentive Processing Audio-Visual Computer-Assisted Self-Interviewing (AVCASI) Autodialer Autodispositioning Automatic Answering Machine Detection Autonomy
  • 4.  Avoiding Refusals Tactics (ART) B Balanced Question Balanced Repeated Replication (BRR) Bandwagon and Underdog Effects Behavioral Question Behavioral Risk Factor Surveillance System (BRFSS) Behavior Coding Beneficence Bias Bilingual Interviewing Bipolar Scale Bogus Question Bootstrapping Bounding Branching Bureau of Labor Statistics (BLS) Busies Back Translation Backward Telescoping Balanced Rank-Set Sample Balanced Rotating Panel Design Base Weight Belmont Report BiweightMidvariance Blocking Blurring Bogus Pipeline Bounded Recall Boxplot Rules Breakoff Buying Cooperation C Callbacks Caller ID Call Forwarding Calling Rules Call-In Polls Call Screening Call Sheet Capture-Recapture Sampling Case Case-Control Study Cell Phone Only Household
  • 5.  Cell Phone Sampling Cell Suppression Census Certificate of Confidentiality Check All That Apply Chi-Square Closed-Ended Question Clustering Cluster Sample Cochran, W. G. (1909-1980) Codebook Coder Variance Coding Cognitive Aspects of Survey Methodology (CASM) Cognitive Interviewing Cold Call Common Rule Completed Interview Completion Rate Complex Sample Surveys Composite Estimation Comprehension Computer-Assisted Personal Interviewing (CAPI) Computer-Assisted Self-Interviewing (CASI) Computer-Assisted Telephone Interviewing (CATI) Computerized-Response Audience Polling (CRAP) Computerized Self-Administered Questionnaires (CSAQ) Confidence Interval Confidence Level Confidentiality Consent Form Constant Construct Construct Validity Consumer Sentiment Index Contactability Contact Rate Contacts Content Analysis Context Effect Contingency Question Contingency Table Contingent Incentives Control Group Controlled Access Control Sheet
  • 6.  Convenience Sampling Convention Bounce Conversational Interviewing Cooperation Cooperation Rate Correlation Council for Marketing and Opinion Research (CMOR) Council of American Survey Research Organizations (CASRO) Covariance Coverage Coverage Error Cover Letter Cronbachs Alpha Crossley, Archibald (1896-1985) Cross-Sectional Data Cross-Sectional Survey Design Current Population Survey (CPS) Cutoff Sampling Calibration Call Center Case Control Form Case Outcome Rates Case Number Case Study Categorical Variable Causal-Comparative Research Choice Questionnaire City Directory Clarification Probe Closed Rings Closeness Property Codec Code Value Labels Coefficient of Variation Coercion Cognitive Burden Cohens Kappa Cohort Panel Survey Cold-Deck Imputation Computer Audio-Recorded Interviewing Concordance Correlation Coefficient Conditional Probability Contingency Test Continuous Random Variable Correction for Attenuation Cost Driver
  • 7.  Cost Object Counting Rule Coverage Rate Cum √f(x) Rule Curb-Stoning D Data Management Data Swapping Debriefing Deception Deliberative Poll Demographic Measure Dependent Interviewing Dependent Variable Designated Respondent Design-Based Estimation Design Effects (deff) Diary Differential Attrition Differential Nonresponse Directory Sampling Disclosure Disclosure Limitation Disk by Mail Dispositions Disproportionate Allocation to Strata Do-Not-Call (DNC) Registries Dont Knows (DKs) Double-Barreled Question Double Negative Drop-Down Menus Dual-Frame Sampling Duplication Data Augmentation Data Coarsening Data Editing Data Shuffling Data Synthesis Declaration of Helsinki Deductive Imputation De-Duping De Facto Residence Rule De Jure Residence Rule Delivery Sequence File (DSF) Deontological Ethics
  • 8.  Descriptive Norms Descriptive Statistic Designated Sample Size Detection Technique Differential Incentive Differential Item Functioning Direct Costs Directed Swapping Direct Estimation Directional Hypothesis Directive Probing Disclosure Avoidance Discrete Random Variable Dispersion Dissemination Unit Doorstep Introduction Dummy Coding E E Ecological Fallacy Economic Exchange Theory Effective Sample Size Election Night Projections Election Polls Elements Eligibility Email Survey Encoding EPSEM Sample Equal Probability of Selection Error of Nonobservation Errors of Commission Errors of Omission Establishment Survey Ethical Principles Event History Calendar Exhaustive Exit Polls Experimental Design External Validity Extreme Response Style Ecological Validity Editing Rules Effect Size Error of Observation
  • 9.  Estimated Best Linear Unbiased Prediction (EBLUP) Estimation Ethnographic Research European Directive on Data Protection Event-Based Diary Event Location Matching Excellence in Media Coverage of Polls Award Expert Sampling F Face-to-Face Interviewing Factorial Design Factorial Survey Method (Rossis Method) Fallback Statements Falsification Fast Busy Favorability Ratings Federal Communications Commission (FCC) Regulations Federal Trade Commission (FTC) Regulations Feeling Thermometer Field Coding Field Director Field Period Field Survey Field Work Final Dispositions Finite Population Finite Population Correction (FPC) Factor Focus Group Forced Choice FRAME Frequency Distribution FRUGing F-Test False Negatives False Positives Family-Wise Error Rate Fear of Isolation Fictitious Question Field Interviewer Field Substitution Filter Question Final Sample Size Fishers Exact Test Fixed Costs Fixed Panel Survey
  • 10.  Flexible Interviewing Following-Rule Follow-Up Mailings Forced Response Technique Foreign Elements Forgiving Wording Forward Telescoping Foveal View Framing G Gallup, George (1901-1984) Gallup Poll Gatekeeper General Social Survey (GSS) Geographic Screening Gestalt Psychology Graphical Language Guttman Scale General Inverse Sampling Generalized Variance Function (GVF) Generic Ballot Question Ghost Numbers Gibbs Sampling Grid Frame Grounded Theory Research H Hagan and Collier Selection Method Half-Open Interval Hang-Up During Introduction (HUDI) Hansen, Morris (1910-1990) Hit Rate Horse Race Journalism Hot-Deck Imputation Household Refusal HTML Boxes Half-Samples Method Hard Refusal Hausman Test Hawthorne Effect Hidden Population Historical Research Homophily Principle Horvitz-Thompson Estimator Household Panel Survey
  • 11.  I Ignorable Nonresponse Imputation Inbound Calling Incentives Independent Variable Ineligible Inference Informant Informed Consent Institute for Social Research (ISR) Institutional Review Board (IRB) Interaction Effect Interactive Voice Response (IVR) Intercoder Reliability Internal Validity International Field Directors and Technologies Conference(IFD&TC) International Journal of Public Opinion Research (IJPOR) International Social Survey Programme (ISSP) Internet Pop-Up Polls Internet Surveys Interpenetrated Design Interrater Reliability Interval Estimate Interval Measure Interviewer Interviewer Characteristics Interviewer Debriefing Interviewer Effects Interviewer Monitoring Interviewer Monitoring Form (IMF) Interviewer Neutrality Interviewer Productivity Interviewer-Related Error Interviewer Training Interviewer Variance Interviewing Intracluster Homogeneity Introduction Inverse Sampling Issue Definition (Framing) Item Order Randomization Item Response Theory Ignorable Sampling Mechanism
  • 12.  Implicit Stratification Incidental Truncation Incorrect Stratum Allocation Incumbent Rule Index of Inconsistency Index of Reliability Indirect Costs Inferential Population Inferential Statistic Injunctive Norms In-Person Survey Interaction Analysis Intercept Polls/Samples Internal Consistency Interquartile Range Inter-University Consortium for Political and Social Research(ICPSR) Interviewer Refusal Aversion Training Interviewer-Respondent Matching Interviewer-Respondent Rapport Interviewer Talk Time Interviewer Training Packet Interviewer Wait Time Intraclass Correlation Coefficient Intraclass Homogeneity Intrusiveness Invariance Issue Publics Item Bank Item Characteristic Curve Item Count Technique Item Nonresponse Item Order Effects J Jackknife Variance Estimation Joint Program in Survey Methodology (JPSM) Journal of Official Statistics (JOS) Judgment Judgmental Sampling Judgment Ranking Juvenile Assent K Key Informant Kish, Leslie (1910-2000)
  • 13.  Kish Selection Method Knowledge Gap Knowledge Question Known Probability of Selection Kuks Card Method L Language Barrier Language Translations Last-Birthday Selection Leaning Voters Level of Analysis Level of Measurement Leverage-Saliency Theory Likely Voter Likert Scale List-Assisted Sampling Listed Number List-Experiment Technique List Sampling Litigation Surveys Log-In Polls Longitudinal Studies Landmark Event Latent Attitude Latent Variable Level of Significance Levels-of-Processing Effect Life Event Calendar Likelihood of Voting Linear Weighting Linguistic Isolation Link-Tracing Design Listed Stratum Listwise Deletion Logical Imputation M Mail Questionnaire Mail Survey Main Effect Mall Intercept Survey Marginals Margin of Error (MOE) Mass Beliefs Matched Number
  • 14.  Mean Mean Square Error (MSE) Measurement Error Median Media Polls Metadata Methods Box Minimal Risk Misreporting Missing Data Mitofsky-Waksberg Sampling Mixed-Mode Mode Mode Effects Model-Based Estimation Mode of Data Collection Mode-Related Error Multi-Level Integrated Database Approach (MIDA) Multi-Mode Surveys Multiple-Frame Sampling Multiple Imputation Multiplicity Sampling Multi-Stage Sample Mutually Exclusive Maintaining Interaction Manifest Variable Mapping Mark-Release-Recapture Sampling Masking Masking Effect Maximum Abandonment Rate Maximum Required Sample Size Mean Imputation Mean Substitution Measured Reliability Measure of Size (MOS) Median Absolute Deviation (MAD) M-Estimation Meta-Analysis Method of Random Groups Microaggregation Missing at Random (MAR) Missing by Design Missing Completely at Random (MCAR) Mixed-Methods Research Design Mock Interviews
  • 15.  Moving Averages Multinomial Sampling Multiple Inverse Sampling Multiplicative Weighting Multiplicity of Elements Murthys Estimator N N National Council on Public Polls (NCPP) National Election Pool (NEP) National Election Studies (NES) National Health and Nutrition Examination Survey (NHANES) National Health Interview Survey (NHIS) National Household Education Surveys (NHES) Program National Opinion Research Center (NORC) Network Sampling New York Times/CBS News Poll Neyman Allocation Nominal Measure Nonattitude NoncausalCovariation Noncontact Rate Noncontacts Noncontingent Incentives Noncooperation Rate Noncoverage Nondifferentiation Nondirective Probing Nonignorable Nonresponse Nonprobability Sampling Nonresidential Nonresponse Nonresponse Bias Nonresponse Error Nonresponse Rates Nonsampling Error Nontelephone Household Nonverbal Behavior Null Hypothesis Number Changed Number Portability Number Verification Nay-Saying Nearest Distance Matching Net Effective Incidence
  • 16.  NeuStar News Polls Next-Birthday Selection Nondirectional Hypothesis Nonobservational Errors Nonzero Probability of Selection NORC Normative Crystallization Normative Intensity Not Missing at Random (NMAR) Number of Strata Nuremberg Code Noncooperation O Open-Ended Question Opinion Norms Opinion Question Opinions Optimal Allocation Ordinal Measure Outbound Calling Outliers Out of Order Out of Sample Overcoverage Overreporting Observational Errors One-and-a-Half-Barreled Question Open-Ended Coding Optimum Stratum Allocation Optimum Stratum Boundaries Original Sample Member Other [Specify] Outcome Rates P Paired Comparison Technique Panel Panel Conditioning Panel Data Analysis Panel Fatigue Panel Survey Paper-and-Pencil Interviewing (PAPI) Paradata Parameter
  • 17.  Partial Completion Percentage Frequency Distribution Percentile Perception Question Perturbation Methods Pew Research Center Pilot Test Point Estimate Political Knowledge Poll Polling Review Board (PRB) Pollster Population Population of Inference Population of Interest Population Parameter Positivity Bias Post-Stratification Post-Survey Adjustments Precision Precision Journalism Precoded Question Predictive Dialing Pre-Election Polls Prefix Pre-Primary Polls Primacy Effect Primary Sampling Unit (PSU) Priming Prior Restraint Privacy Privacy Manager Probability Probability of Selection Probability Proportional to Size (PPS) Sampling Probability Sample Probable Electorate Probing Propensity Scores Propensity-Weighted Web Survey Proportional Allocation to Strata Protection of Human Subjects Proxy Respondent Pseudo-Polls Psychographic Measure Public Opinion
  • 18.  Public Opinion Quarterly (POQ) Public Opinion Research Purposive Sample Push Polls Pairwise Deletion Panel Attrition Panel Management Paralinguistic Communication Parallel Forms Consistency Parallel Retrieval Parental Consent Part-Whole Contrast Effects Passive Screening Percentage Bend Midvariance Percentile Point Percentile Rank Permanent Random Number Technique Persuaders Phenomenological Research Placebo Plausible Values Play-the-Winner Sampling Plot Frame Population Characteristics Population Variance Post-Coding Post-Imputation Variance Estimates Post-Randomization Method Power Pre-Attentive Processing Pre-Coding Predictor Variable Prenotification Presidential Approval Pre-Survey Notification Pretest Sensitization Effects Prevention Technique Preview Dialing Prime Telephone Numbers Principles of Disclosure Proactive Dependent Interviewing Probability Minimum Replacement (PMR) Sampling Process Data Processing Errors Production Rate Proportionate Random Sample
  • 19.  Pseudo-Opinion Pseudo-Panels Pseudorandom Numbers Public Judgment Pretest Q Quality Control Quality of Life Indicators Questionnaire Questionnaire Design Questionnaire Length Questionnaire-Related Error Question Order Effects Question Stem Question Wording as Discourse Indicators Quota Sampling Quality Circle Meetings Questionnaire Translation R Radio Buttons Raking Random Random Assignment Random-Digit Dialing (RDD) Random Error Randomized Response Random Order Random Sampling Random Start Ranked-Set Sampling (RSS) Ranking Rare Populations Rating Ratio Measure Raw Data Reactivity Recency Effect Recoded Variable Recontact Record Check Reference Period Refusal Refusal Avoidance Refusal Avoidance Training (RAT)
  • 20.  Refusal Conversion Refusal Rate Refusal Report Form (RRF) Registration-Based Sampling (RBS) Regression Analysis Reinterview Relative Frequency Reliability Repeated Cross-Sectional Design Replacement Replicate Methods for Variance Estimation Replication Representative Sample Research Call Center Research Design Research Hypothesis Research Management Research Question Residence Rules Respondent Respondent Burden Respondent Debriefing Respondent-Driven Sampling (RDS) Respondent Fatigue Respondent-Interviewer Rapport Respondent Refusal Respondent-Related Error Response Response Alternatives Response Bias Response Latency Response Order Effects Response Propensity Response Rates Retrieval Reverse Directory Reverse Directory Sampling Reverse Record Check Rho Role Playing Rolling Averages Roper, Elmo (1900-1971) Roper Center for Public Opinion Research Rotating Panel Design Randomization Test Random Swapping
  • 21.  Rank Swapping Ratio Estimation Reactive Dependent Interviewing Recall Loss Recognition Reference Survey Regression Estimation Regression Imputation Reminder Mailings Replacement Questionnaire Replicate Replication Weights Reporting Unit Respondent Autonomy Respondent-Interviewer Matching Respondent Number Respondent Rights Response Error Return Potential Model Rotation Group Bias Rotating Groups Rounding Effect Round-Robin Interviews S Saliency Sample Sample Design Sample Management Sample Precinct Sample Replicates Sample Size Sampling Sampling Bias Sampling Error Sampling Fraction Sampling Frame Sampling Interval Sampling Pool Sampling Variance Sampling Without Replacement SAS Satisficing Screening Seam Effect Segments
  • 22.  Self-Administered Questionnaire Self-Reported Measure Self-Selected Listener Opinion Poll (SLOP) Self-Selected Sample Self-Selection Bias Semantic Differential Technique Sensitive Topics Sequential Sampling Sheatsley, Paul (1916-1989) Show Card Significance Level Simple Random Sample Small Area Estimation Snowball Sampling Social Capital Social Desirability Social Exchange Theory Social Isolation Solomon Four-Group Design Spiral of Silence Split-Half Standard Definitions Standard Error Standard Error of the Mean Standardized Survey Interviewing STATA Statistic Statistical Package for the Social Sciences (SPSS) Statistical Power Statistics Canada Step-Ladder Question Strata Stratified Sampling Straw Polls Subgroup Analysis SUDAAN Suffix Banks SUGING Superpopulation Supervisor Supervisor-to-Interviewer Ratio Survey Survey Costs Survey Ethics Survey Methodology Survey Sponsor
  • 23.  Systematic Error Systematic Sampling Sales Waves Salting Sample Variance Sampling Paradox Sampling Precision Sampling Unit Sampling With Replacement Secondary Sampling Unit (SSU) Secondary Telephone Numbers Selectivity Bias Self-Coding Self-Disqualification Self-Weighting Sample Semantic Text Grammar Coding Semi-Structured Interviews Sequential Retrieval Serial Position Effect Silent Probe Single-Barreled Question Single-Stage Sample Skip Interval Skip Pattern Social Barometer Social Well-Being Soft Refusal Specification Errors Statistical Disclosure Control Statistical Inference Statistical Perturbation Methods Straight-Lining Stratification Stratified Cluster Sampling Stratified Element Sampling Stratified Random Assignment Stratum Allocation Stringer Structured Interviews Subclasses Subsampling Substitution Summer Institute in Survey Research Techniques Supersampling Suppression Survey Packet
  • 24.  Survey Population Synthetic Estimate T Tailoring Target Population Taylor Series Linearization (TSL) Technology-Based Training Telemarketing Telephone Consumer Protection Act of 1991 Telephone Households Telephone Penetration Telephone Surveys Telescoping Temporary Dispositions Test-Retest Reliability Third-Person Effect Topic Saliency Total Design Method (TDM) Total Survey Error (TSE) Touchtone Data Entry Tracking Polls Training Packet Trend Analysis Trial Heat Question Troldahl-Carter-Bryant Respondent Selection Method True Value Trust in Government Type I Error Type II Error Taboo Topics Tailored Design Method Targeting Teleological Ethics Telephone Computer-Assisted Self-Interviewing (TACASI) Telephone Interviewer Telesurveys Temporary Sample Member Temporary Vacancy Text Fills Think-Aloud Interviews Threatening Question Time-Based Diary Time Compression Theory Time-in-Panel Bias Time-Space Sampling
  • 25.  Tolerance Interval Trimmed Means Turnout Score Two-Stage Sample U Unable to Participate Unaided Recall Unavailable Respondent Unbalanced Question Unbiased Statistic Undecided Voters Undercoverage Underreporting Unfolding Question Unit Unit Coverage Unit Nonresponse Unit of Observation Universe Unknown Eligibility Unlisted Household Unmatched Number Unpublished Number Usability Testing U.S. Bureau of the Census Ultimate Sampling Unit Undue Influence Unimode Design Universe Estimates (UEs) Unmatched Count Technique Unrelated Question Technique Unrestricted Random Sample Unstructured Interviews U.S. Census Bureau Usual Residence Unequal Probability of Selection V Validation Validity Variable Variance Variance Estimation Verbatim Responses Verification
  • 26.  Video Computer-Assisted Self-Interviewing (VCASI) Videophone Interviewing Vignette Question Visual Communication Voice over Internet Protocol (VoIP) and the Virtual Computer-Assisted Telephone Interview (CATI) Facility Voluntary Participation Value Labels Variable Costs Variance Theory Variance Unit Vector-at-a-Time Sampling Venue Sampling Verbal Probing Virtual Training Environment Voter News Service W Wave Web Survey Weighting WesVar Within-Unit Coverage Within-Unit Coverage Error Within-Unit Selection World Association for Public Opinion Research (WAPOR) Wave Nonresponse Weighted Kappa Winsorization Winsorized Variance Y Yea-Saying Z Zero-Number Banks Zero-Listed StratumSearch all journals on:Related TitlesLoading ...
  • 27. Related listso methodo Interviewso SSRMo Communication Researcho Communication Researcho Communication ResearchMy Methods Lists: To see My Methods Lists, click here to sign in.Articles in Google Scholar byM. H. ClarkWilliam R. ShadishCopyright © 2013Privacy PolicyCreditsTerms of UseContact UsAwards and ReviewsMethodspace | Connecting the research communityGive us your feedback.Experimental DesignsTrue experiments tend to be difficult to set up and complete properly, but in many casesthey are relatively straightforward to analyze and interpret once the results are collected.They can, however, become fairly complex in cases where more than one treatment ortreatment level are being tested, and there can also be the temptation to do what is called"data fishing", or post hoc analysis. For now, tuck away in the back of your mind thatthere are ways to do post hoc analysis and ways - not - to do this. You can learn more aboutpost hoc analyses once you learn the basics.The designs discussed starting on this page are the most common experimental designs.There are others, and experiments can actually be constructed in "building block" or"factorial" fashion, but this is a rather complex enterprise. Trust me on this one. If youwant to learn more about factorial design, here is a reference.
  • 28. RandomizationFirst and foremost, learn to think of the people who participate in your experiment, controlgroup(s) as well as experimental group(s) as representatives. They represent persons whomay receive the new treatment or procedure in the future, if your experiment yieldspromising results. Persons in the control group as well as the experimental group must beequally likely candidates, and, to be really correct, the persons who participate in yourexperiment should be drawn randomly from all persons who could conceivably becandidates for the new treatment or procedure. (This last condition is rarely feasible, butyou need to be aware of it.) Drawing from the total population of all possible candidates israndom selection. Once a pool of participants is randomly selected, they are randomlyassigned to experimental or control group(s).The Posttest-Only Control Group DesignThis design can be diagrammed as follows:We shall start our discussion of the true experimental designs with the Posttest-OnlyControl Group Design, as this is the simplest possible form of the true experiment.The Pretest-Posttest Control Group DesignThis design can be diagrammed as follows:Randomization is used in the Posttest-Only Control Group design to create a situation ofinitial statistical equivalence of the experimental and control groups. Under someconditions, however, it is desirable to actually measure certain participant characteristics
  • 29. before commencing the experiment. The simplest means of accomplishing this is to use thePretest-Posttest Control Group design.The Solomon Four-Group DesignThis design can be diagrammed as follows:The Solomon Four-Group Design is a very tight experimental design, controlling well forboth internal and external potential sources of error or ambiguity.Summary