INTER-SECTION Volume III - Page 35

| Detecting Social Change | between two variables within categorical data. It demonstrates an association between variables and whether the outcome is statistically significant (Fletcher and Lock 2005, 125). When the outcome of the Chi-squared method is close to zero then there is no evidence of association (Fletcher and Lock 2005, 131). There is a significant relation between evidence when the result is equal to or larger than χ 2 = 3.84 (Fletcher and Lock 2005, 202). Results were determined to be statistically significant when the P-value was equal or below the 0.05 level. Results In total, the data from 9556 individuals analysed by MOLA were available for this research. From the nine Medieval cemeteries included in the WORD database and monographs, 6060 adults were analysed of which nine individuals showed skeletal changes conforming osteoporosis. Of the sixteen post-Medieval cemeteries evaluated, which contained 3496 adults, 76 individuals show skeletal changes diagnosed as (possible) osteoporosis. The distribution per site of males and females of different ages affected with osteoporosis can be found in the previous mentioned overview tables: 1a and 1b. The CPR calculated for the Medieval period is 0.07%. Three of the sites contained zero individuals with in their excavated population with osteoporosis. The calculated CPR for the post-Medieval period is higher with 1.08%. Five cemeteries contained no individuals with osteoporosis. However, four post-Medieval cemeteries exceed this average post-Medieval CPR with large numbers. These cemeteries are: St Benet Sherehog (post-Medieval graves) with 2.55%, Chelsea Old Church with 3.79%, St Bride’s Church Fleet Street with 3.96% and St Brides Lower Cemetery with 5.16%. Overall, the result of the Chi-squared test demonstrated prevalence of osteoporosis between the samples from the two periods (P-value = < 0.0001, χ 2 = 100.879, 1df). These results demonstrate that here is more osteoporosis in the post-Medieval period. Since osteoporosis can be linked to sex, it is useful to look at statistical differences between males and females with osteoporosis in the Medieval and post- Medieval period. However, the number of affected adults in the Medieval period is too small to make any meaningful comparisons. The result for the post-Medieval period (tab. 2a) shows an extremely and osteoporosis (P-value = < 0.0001, χ 2 = 33.707, 1df). This indicates that females are more affected with osteoporosis than males in this period. post-Medieval Males post-Medieval Females Total OP No OP Total 57 1183 1240 14 71 1459 2642 1473 2713 Table 2a. Contingency table for analysed males and females from the post-Medieval period. Medieval Males OP No OP Total 14 1459 1473 3 post-Medieval Males Total 17 3253 4712 3256 4729 Table 2b. Contingency table for analysed males with osteoporosis between periods. Medieval Females post-Medieval Females Total OP No OP Total 57 1183 1240 5 62 2142 3325 2147 3387 Table 2c. Contingency table for analysed females with osteoporosis between periods. To assess if one or both sexes were more or less affected, prevalence rates were calculated for each sex. To assess whether osteoporosis prevalence rates differed between Medieval and post-Medieval males, their prevalence rates were compared (tab. (P-value = < 0.0001, χ 2 = 18.531, 1df). The relationship for females with osteoporosis (tab. 2c) between the Medieval and post-Medieval period 2 = 80.887, 1df). This suggests that both sexes are more affected with osteoporosis in the post-Medieval period. post-Medieval 36-45 Years post-Medieval ≥46 Years Total OP No OP Total 59 683 742 6 65 650 1333 656 1398 Table 2d. Contingency table for individuals with osteopo- rosis in two different age categories for the post-Medieval period. 2017 | INTER-SECTION | VOL III | p.33