Found in 1-3% of methodology chapters. If Chapter 3 says 15 participants and Chapter 4 reports data from 12, your committee's first question is: what happened to the other three?
Ensure sample size numbers are consistent throughout the chapter.
Sample size inconsistency is one of the most easily avoidable errors in a dissertation, and one of the most damaging when it slips through. When you state different participant numbers in different sections without explanation, your committee questions the rigor of your entire study. Did you lose participants? Did you miscalculate? Did you not proofread? None of those possibilities reflect well on your research.
These inconsistencies typically emerge during the long revision process. You wrote Chapter 3 with a planned sample of 15, conducted the study with 12 (three dropped out), reported findings for 12 in Chapter 4, but never went back to update Chapter 3. Or you have 20 survey respondents but only 18 completed all items, and you switch between the two numbers without explaining the difference.
Every mention of your sample size should be consistent, or the discrepancy should be explicitly explained. "The researcher recruited 15 participants; 12 completed the full study (see Attrition, Section 4.2)" is transparent and professional. Saying 15 in one place and 12 in another without explanation is a red flag that invites scrutiny of everything else in your data.
Conflicting sample size numbers across sections signal carelessness and undermine the credibility of the entire methodology.
A total of 15 participants were interviewed... The 12 interviewees provided rich data.
A total of 15 participants were interviewed... The 15 interviewees provided rich data across three rounds of interviews.
Discrepancy explained explicitly with attrition details in both chapters.
Chapter 3: "The sample will consist of 15 teachers." Chapter 4: "Twelve participants completed the interview protocol."
Chapter 3: "The researcher recruited 15 teachers; 12 completed all phases of data collection (see Section 4.1 for attrition details)." Chapter 4: "Of the 15 recruited participants, 12 completed the full interview protocol. Three withdrew prior to the first interview due to scheduling conflicts."
Response rate documented and cross-referenced between methodology and findings.
Section 3.4: "Twenty surveys were distributed." Section 4.2: "Survey results from 18 respondents revealed..."
Section 3.4: "Twenty surveys were distributed; 18 were returned complete (90% response rate)." Section 4.2: "The 18 completed surveys (see Section 3.4) revealed..."
All three numbers are accurate but need a narrative explaining the progression from 30 to 22.
The abstract states N=25. Chapter 3 describes N=30. Chapter 4 analyzes N=22.
Thirty participants were initially recruited. Five did not meet inclusion criteria after screening, and three withdrew during data collection, resulting in a final sample of 22 participants (see Section 4.1).
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