Sampling
In this cross-sectional prospective study, 572 volunteer adult students (286 males and 286 females) of age group 18 to 26 years studying in Debre Markos University were selected using a multi-stage sampling method. Debre Markos University has six colleges, two schools, and two institutions. The primary sampling units (PSU) were selected by lottery method as colleges, schools, and institutions. Secondary sampling units (SSU) were also selected by lottery method from primary sampling units as departments. The tertiary sampling units (TSU) were students and selected by simple random sampling method according to inclusion criteria. The PSUs were Health Science College, Technology College, Agriculture and Natural Resource College, School of Law, and Institution of Education and Behavioral Sciences. The SSUs were departments such as Public Health, Nursing, Midwifery, Civil Engineering, Electrical Engineering, Construction Management, Natural Resource Management, Animal Science, Psychology, and School of law. The TSUs were students and interviewed and measured according to inclusion criteria until the desired sample size was attained. The number of male and female students was proportional from the total sample size, 572. Oral interview revealed that the selected participants were only Ethiopian parental roots and came from Amhara, Oromo, Tigray, Southern Nations, Nationalities, and Peoples’ Region (SNNP), Afar, Gambella, and Benishangul-Gumuz ethnicities. Participants without any obvious congenital or acquired deformity of the spine, extremities, and head and who volunteered to participate were included in the study. Participants that have deformities of the spine, extremities, and significant growth disorder were excluded from the study. Furthermore, the acutely ill, the physically challenged, any individuals known to be on some form of continuous medication or being in a poor state of health manifesting with overt signs of stunting, physical emaciation, and grotesque obesity were also excluded. Data were collected from April 2018 to December 2018.
Anthropometry
Equipment
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1.
Stadiometer (PRESTIGE)
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2.
Non-elastic measuring tape meter
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3.
Digital sliding caliper
Measurement techniques
Standing height was measured to the nearest 0.1 centimeters (cm) using a stadiometer with the subject standing erect on a horizontal resting plane, barefooted, having palms of hands turn inward, and fingers pointing downwards. The head was adjusted in the Frankfurt horizontal plane. All measurements were taken by bringing the sliding horizontal bar up on the vertex. It was measured from the sole of the feet to the vertex of the head as recommended by the International Biological Program (Ibegbu et al. 2015) (Fig. 1).
For measuring the percutaneous length of the tibia, the person was asked to sit on a stool so that the thigh should be placed in a straight line, and the leg and thigh should be placed right angle to each other (maintain the angle of 90°with each other); the foot was rotated laterally, so that the bony projection were prominently seen. Then, proximal and distal points of the tibia were marked by a marker pencil. Then, the two points (proximal and distal) were measured by non-elastic measuring tape meter and sliding caliper. Then, the tibial length was measured between the medial most superficial point on the upper border of medial condyle of the tibia and the tip of the medial malleolus (Trotter and Gleser 1952) (Fig. 2).
Data quality control
Data were collected by two personnel: one male (Bachelor of Science in Public Health) and one female (Bachelor of Science in Midwifery). To maintain data quality, training was given for data collectors about anthropometric measurements and measurement errors. Data collectors had reliability testing as part of the training, aimed to achieve technical errors within internationally accepted limits. All measurements were taken by the trained tester/measurer. Properly designed data collection materials were prepared. Supervision was carried out by the principal investigator during data collection times to check completeness and consistency of data. The reliability and representativeness of data were also maintained by incorporating only complete data of study participants with in the study period.
Statistical analysis
Data were entered in EPI data version 3.1 and analyzed using SPSS version 25 statistical software. Data were analyzed for mean, standard deviation, and standard errors of estimate (SEE), using independent and paired t tests. The Kolmogorov-Smirnov test was carried out to determine the normality of the samples. Independent t test was used to assess the evidence of sexual dimorphism in the study samples. The paired t test was also used to determine the existence of bilateral asymmetry. Significance levels for differences were set at P < 0.05 (with 95% confidence interval). The Pearson’s correlation coefficients (R) were adopted as the measure of strength of the association between height and percutaneous tibial length for both males and females. Coefficient of determination (R2) was estimated to determine how much of the variance in the dependent variable could be explained by its relationship to the other variables. Linear regression equations were derived as predictive models for body height estimation from percutaneous tibial length.