Here is a list of 100 research methodologies used across various fields, from social sciences to natural sciences and engineering:
1. Quantitative Research
2. Qualitative Research
3. Mixed-Methods Research
4. Case Study Research
5. Action Research
6. Experimental Research
7. Quasi-Experimental Research
8. Survey Research
9. Phenomenological Research
10. Ethnographic Research
11. Grounded Theory
12. Content Analysis
13. Historical Research
14. Narrative Inquiry
15. Correlational Research
16. Comparative Research
17. Longitudinal Research
18. Cross-Sectional Research
19. Causal-Comparative Research
20. Action-Design Research
21. Observational Research
22. Experimental Design (Randomized Controlled Trials)
23. Field Research
24. Archival Research
25. Laboratory Research
26. Focus Group Research
27. Delphi Method
28. Content Analysis (Qualitative)
29. Usability Testing
30. Longitudinal Cohort Studies
31. Systematic Review
32. Meta-Analysis
33. Statistical Modeling
34. Computer Simulation
35. Genetic Studies
36. Cross-Cultural Research
37. Statistical Process Control
38. Action-Research Cycles
39. Narrative Analysis
40. Participatory Action Research
41. Interviews (Structured, Semi-Structured, Unstructured)
42. Cluster Analysis
43. Regression Analysis
44. Principal Component Analysis (PCA)
45. Factor Analysis
46. Cluster Sampling
47. Snowball Sampling
48. Random Sampling
49. Stratified Sampling
50. Convenience Sampling
51. Delphi Study
52. Secondary Data Analysis
53. Phenomenographic Research
54. Comparative Effectiveness Research
55. Grounded Action Research
56. Data Mining
57. Content Validity Testing
58. Network Analysis
59. Longitudinal Tracking
60. Exploratory Research
61. Confirmatory Research
62. Thematic Analysis
63. Discourse Analysis
64. Semiotic Analysis
65. Hermeneutic Research
66. Interpretative Phenomenological Analysis (IPA)
67. Explanatory Case Study
68. Experimental Simulation
69. Computational Modeling
70. Evaluative Research
71. Design-Based Research
72. Participatory Research
73. Evaluative Interviews
74. Behavioral Research
75. Textual Analysis
76. Actionable Research
77. Design Thinking
78. Visual Ethnography
79. System Dynamics Modeling
80. Cognitive Task Analysis
81. Virtual Ethnography
82. Online Surveys
83. Statistical Process Modeling
84. Public Policy Analysis
85. Impact Evaluation
86. Program Evaluation
87. Field Trials
88. Biographical Research
89. Ethical Hacking
90. Critical Discourse Analysis
91. Survey Experimentation
92. Participatory Mapping
93. Deliberative Polling
94. Policy Research
95. Spatial Analysis
96. Ecological Study
97. Simulation Modeling
98. Realist Evaluation
99. Fuzzy Logic Analysis
100. Bayesian Inference
Each methodology serves a distinct purpose and is suitable for different types of research questions, data types, and disciplines. Depending on the research goals, one may use several in tandem, especially in mixed-methods approaches.