How to Calculate Sample Size for Different Study Designs in Medical Research?

Charan, Jaykaran; Biswas, Tanmay

doi:10.4103/0253-7176.116232

Cited by 1,980 publications

(1,492 citation statements)

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“…[7] To calculate the sample size with precision/absolute error meet of 5% and type 1 error of 5%, the following formula was used: Sample size = [2 × (SD obtained from a previous study) 2 × (Z α/2 + Z β ) 2 ] / mean difference obtained from previous study. [11] Therefore, n = [2 × (463) 2 × (1.96 + 0.84) 2 ] / [3,503 -3,215] = 142.02. Accordingly, the sample size required in this study was 143 women with their neonates.…”

Section: Sample Size Calculationmentioning

confidence: 99%

Maternal and neonatal predictive variables for quality of cord blood as a source of stem cells

Marzouk

Abd-Allah²

2018

JNEP

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Objective: This study aimed to identify the maternal and neonatal predictive variables for quality of cord blood as a source of stem cells. Methods: A descriptive design was followed in this study. A purposive sample of 143 pairs; pregnant women assigned for elective cesarean section and their newborns, was enrolled in current study. The subjects were recruited from the Operating Theater of Mansoura University Hospital, Egypt. One hundred forty three umbilical cord blood units were collected in utero from cesarean deliveries. The collected units were assessed for its blood volume and total nucleated cells content. An assessment sheet of 12 items was used as a tool of data collection. Results: The greater blood volume and higher nucleated cells obtained from the primigravida, between 37 to 40 gestation weeks, and those not exposed to cigarette smoke during pregnancy (163.1 ± 24.8 ml and 10.2 ± 2.8 × 10 6 cells/ml, 169.3 ± 22.6 ml and 11.2 ± 1.9 × 10 6 cells/ml, 169.8 ± 21.4 ml and 10.0 ± 2.9 × 10 6 cells/ml respectively). The birth weight ≥ 3,600 g, the first born baby, and the heavier placenta (≥ 550 g) produced significantly greater blood volume and cellular content (161.5 ± 20.6 ml and 9.8 ± 2.4 × 10 6 cells/ml, 164.6 ± 19.4 ml and 9.6 ± 2.7 cells/ml, 164.8 ± 19.6 ml and 10.2 ± 2.6 × 10 6 cells/ml respectively). Conclusions: Primigravida, delivery between 37 to 40 gestation weeks, and no exposure to cigarette smoke during pregnancy were the maternal variables that were associated with larger blood volume and higher cellular content. Even though, first born baby, birth weight ≥ 3,600 g, and placenta weight ≥ 550 g were the neonatal variables.

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Section: Sample Size Calculationmentioning

confidence: 99%

Maternal and neonatal predictive variables for quality of cord blood as a source of stem cells

Marzouk

Abd-Allah²

2018

JNEP

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“…The population used in this study was children less than 1 year old in 12 selected communities in 6 LGAs in the 3 senatorial districts of Rivers State. The population of Nigeria is estimated to be at about 167 million (2006 census report) and children under 1 year of age constitute 4% (6.6 million) of the total population (NPHCDA) [3].…”

Section: Study Populationmentioning

confidence: 99%

“…The sample size for this study was based on formula [6]. However, for a representative sample population for the study, the number was increased proportionally from the selected communities, giving 1,100 infants which are greater than 3% of the prevalence value considering the lower prevalence rate of 10% that may progress to moderate to severe cases.…”

Section: Determination Of Sample Sizementioning

confidence: 99%

The Relationship of Gender in the Pattern and Risk of Acute Respiratory Infection among Infants in Rivers State, Nigeria

Owens¹,

Harper²,

Sd³

et al. 2017

J Community Med Health Educ

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Statement of the problem: Gender had a much wider influence on disease than is usually acknowledged. More so, relative contributions of social and biological factors had not been clearly delineated for many diseases. Higher mortality rates are usually observed in male infants with lower acute respiratory infections (ARIs) and pneumonia particularly during the first month of life than the female infants due to immature lungs in males. The rate declines between 6 and 12 months after birth. The study aims to determine the existence and pattern of relationship between risk of ARI and gender. Methodology and theoretical orientation:The study was designed as a community based retrospective casecontrol study of 1,100 infants randomly selected from 12 communities out of 6 Local Government Areas of the 3 senatorial districts of Rivers State. A multistage random sampling technique was used in selecting the subjects up to the community level. Descriptive method was used to represent the characteristics of the subjects and the differences in ARI between male and female infants were tested in a bivariate logistics regression at 5% level of significance. Odds ratio (OR) were used to interpret the size effect measures of ARI on gender differences. Findings:A total of 275 Cases of ARI and 825 controls were included in the study. The ARI cases were found to be slightly higher in Female infants (27.8%) than in the Male infants (22.4%). For the Female infants, the odds for ARI were 1.3 times significantly higher compared to those of their Male counterparts (OR=1.32, p=0.048, 95%CI=1.003-1.735). Conclusion and significance:Understanding such differences between Male and Female infants will enhance the knowledge about the epidemiology, outcome and effectiveness in prevention and control of ARIs.Recommendation: Awareness creation on gender differences in susceptibility to acute-respiratory infection among infants requires sustainable attention.

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“…The study we used was closest to our design. The calculation of sample size depends on whether the outcome variable is quantitative or qualitative [3]. When qualitative parameters are used, sample size required is larger.…”

Section: To the Editormentioning

confidence: 99%