Σύγκριση μεθόδων

	Έρευνα με Δείγμα	Τεχνική Delphi	Συνέντευξη πρόσωπο με πρόσωπο	Διαχρονική Έρευνα	Μεικτή Έρευνα (Mixed Methods Research)
Πεδίο	Μεθοδολογία Επισκοπήσεων	Μεθοδολογία Επισκοπήσεων	Μεθοδολογία Επισκοπήσεων	Μεθοδολογία Επισκοπήσεων	Ποιοτικές Μέθοδοι
Οικογένεια	Process / pipeline	Process / pipeline	Process / pipeline	Process / pipeline	Process / pipeline
Έτος προέλευσης	Late 19th century; systematic social-science use from 1940s	1950s–1963	1930s–1940s (systematic survey era)	1940s (panel survey tradition); longitudinal designs codified mid-20th century	—
Δημιουργός	Francis Galton, Charles Booth, and early social statisticians; formalised by Paul Lazarsfeld in the 1940s	Norman Dalkey and Olaf Helmer (RAND Corporation)	Established practice formalised in survey methodology (Gallup, Likert, and others from the 1930s–1940s)	Established tradition; formalized in social science by Paul Lazarsfeld and colleagues (1940s panel studies)	—
Τύπος	Quantitative (primarily) or mixed-methods data-collection instrument	Iterative expert consensus technique	Quantitative / mixed-mode data collection	Quantitative / mixed-methods survey design	Research design framework
Θεμελιώδης πηγή	Dillman, D. A., Smyth, J. D., & Christian, L. M. (2014). Internet, Phone, Mail, and Mixed-Mode Surveys: The Tailored Design Method (4th ed.). Wiley. ISBN: 978-1118456149	Dalkey, N., & Helmer, O. (1963). An experimental application of the Delphi method to the use of experts. Management Science, 9(3), 458–467.	Fowler, F. J. (2014). Survey Research Methods (5th ed.). Sage Publications. ISBN: 978-1452259000	Menard, S. (2002). Longitudinal Research (2nd ed.). Sage Publications. ISBN: 978-0761922292	Creswell, J.W. & Plano Clark, V.L. (2018). Designing and Conducting Mixed Methods Research (3rd ed.). Sage. ISBN: 978-1483344379
Εναλλακτικές ονομασίες	questionnaire survey, survey research, self-report survey, questionnaire study	Delphi method, Delphi survey, expert consensus method, iterative expert panel	personal interview survey, in-person survey, PAPI survey, door-to-door survey	panel survey, repeated-measures survey, longitudinal panel study, wave survey	Karma Yöntem Araştırması (Mixed Methods), multi-method research, triangulation design
Συναφείς	6	6	5	3	4
Σύνοψη	A survey is a systematic data-collection method in which a standardised set of questions is posed to a sample of respondents to measure attitudes, behaviours, demographics, or other constructs. Surveys can be administered via paper, telephone, online platforms, or face-to-face. They are among the most widely used instruments in social, behavioural, health, and educational research because they can reach large, geographically dispersed samples at relatively low cost.	The Delphi technique is a structured, multi-round data collection method that harvests and refines expert opinion through iterative questionnaires and controlled feedback. Developed at RAND Corporation in the 1950s, it is designed to converge a dispersed expert panel toward a reliable consensus on complex, uncertain, or future-oriented questions — without the conformity pressures of face-to-face group discussion.	A face-to-face survey is a structured data collection method in which a trained interviewer meets respondents in person and administers a standardised questionnaire. The interviewer reads questions aloud, clarifies wording when permitted by protocol, and records answers — either on paper (PAPI) or a laptop/tablet (CAPI). This mode consistently achieves higher response rates and better data quality for complex or sensitive questionnaires than self-administered alternatives, and is the reference standard in large-scale population surveys.	A longitudinal survey collects structured questionnaire data from the same individuals or units at two or more distinct points in time. By tracking the same respondents across waves, researchers can distinguish genuine change from stable individual differences, establish temporal ordering between variables, and model trajectories of attitudes, behaviors, or outcomes in ways that a single cross-sectional snapshot cannot support.	Mixed methods research is a systematic research design in which quantitative and qualitative data are collected and analysed within a single study. Formalised by Creswell and Plano Clark (2003, 3rd ed. 2018), it offers three principal design variants — concurrent, sequential, and transformative — and strengthens findings through triangulation across both data strands.