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Analyzing Bone Femur Length in Ancient Cultures: A Comparative Study in STATA

Our STATA assignment involves a comprehensive analysis of Bone Femur Length (BFL) among individuals from two distinct ancient cultures, the Jomon and Yayoi. This comparative study sheds light on the differences and similarities in BFL across genders and cultures. We present a detailed summary of our findings, along with visual aids, to provide a clear and concise overview of our analysis. Explore the insights gathered from summary statistics, box plots, and Z-scores to gain a deeper understanding of how BFL varies between these ancient populations.

Problem Description:

The aim is to explore and compare the physical characteristics of individuals from two different ancient cultures, Jomon and Yayoi, with a focus on Bone Femur Length (BFL). We examine summary statistics, visualize the data using box plots, and analyze Z-scores to draw conclusions about the similarities and differences in BFL between the two cultures and across genders.


Table 1: Summary statistics

Descriptive Statistics

Culture Sex N Minimum Maximum Mean Median Mode Range Std. Deviation
Jomon 1 BFL 29 38 45 41.28 41.50 39 7 1.753
2 BFL 14 36 44 38.48 37.90 36 8 2.355
Yayoi 1 BFL 23 35 47 42.44 42.80 42 12 2.893
2 BFL 20 36 44 39.72 39.65 36 8 2.391

From Table 1, it is very clear that the central tendencies (Mean, Median and Mode) and dispersions (Range and Standard deviation) of BFL for Jomon male is not similar to that of Jomon female. Similarly, the statistics are not similar for Yayoi male and Yayoi female. However, Jomon male and Yayoi male have similar central tendencies and dispersions of BFL likewise Jomon female and Yayoi female as evident in the table.

Box plot

Box Plot

Figure 1: Box plot by Sex by Culture

Figure 1 contains box plots of BFL categorized by sex and culture. Since both sex and culture have two categories each, four box plots are been produced which are meant for Jomon male, Jomon female, Yayoi male and Yayoi female as displayed in the above figure.

Except for Yayoi (sex=2), the remaining three box plots exhibit non-normality as a result of unequal box and whiskers lengths. The interquartile ranges (Q3-Q1) which is the length of the box do not overlap for Jomon males and Jomon females since the boxes for Jomon males is completely above that of Jomon females. Similarly, the boxes do not overlap for Yayoi males and Yayoi females since the box for Yayoi males is completely above that of Yayoi females.

The medians for Jomon males and Jomon females do not overlap because the median line of Jomon male lie outside of Jomon female box. Also, the medians for Yayoi males and Yayoi females do not overlap because the median line of Yayoi male lie outside of Yayoi female box.

We can support the hypothesis that one group had larger femora based on these observations or that one group was more or less variable since we have non-overlapping boxes and the medians do not overlap with the boxes.

Distribution of Z scores

Distribution of Z scores

Figure 2: Box plot of Z-scores by Culture by sex

Figure 2 contains box plots of Z scores BFL. The plots reveal that the boxes of Jomon and Yayoi males do overlap. Also, the boxes of Jomon and Yayoi females overlap as displayed in the figure. The boxes do not spread beyond the medians. This implies that BFL in Jomon and Yayoi groups are likely to be the same.