Identifying patterns of distribution in olive oil trade 1 Xavier - PowerPoint PPT Presentation

Identifying patterns of distribution in olive oil trade 1 Xavier Rubio-Campillo – xavier.rubio@ed.ac.uk @xrubiocampillo

A wishlist for Roman economy

A wishlist for Roman economy

A wishlist for Roman economy

A wishlist for Roman economy

Quantifying Roman economy Broekaert, W. (2011). Oil for Rome during the second and third century AD: a confrontation of archaeological records and the Historia Augusta. Mnemosyne , 64(4), 591–623.

Quantifying Roman economy Temin, P., 2013. The Roman Market Economy . Princeton University Press, p.75

Quantifying Roman economy Low sample size

Quantifying Roman economy Low sample size Archaeological biases

Quantifying Roman economy Low sample size Multiple proxies Archaeological biases

Quantifying Roman economy High uncertainty Low sample size Multiple proxies Archaeological biases

The challenges of the fjeld We need informative proxies of economic activity We need to use methods able to tackle these challenges

Amphoric stamps as proxies Previous research suggests that the frequency distribution of amphoric stamps is a good proxy of economic activities

Amphoric stamps as proxies Previous research suggests that the frequency distribution of amphoric stamps is a good proxy of economic activities

Amphoric stamps as proxies Previous research suggests that the frequency distribution of amphoric stamps is a good proxy of economic activities “Our results show that the size of the economic agents involved in this massive market followed a power-law distribution. As a consequence, the model selection framework strongly indicates the presence of free market structures within the olive oil production feeding the city of Rome.” Rubio-Campillo, X. et al. In press. Bayesian analysis and free market trade within the Roman Empire, Antiquity .

Amphoric stamps as proxies Previous research suggests that the frequency distribution of amphoric stamps is a good proxy of economic activities “Our results show that the size of the economic agents involved in this massive market followed a power-law distribution. As a consequence, the model selection framework strongly indicates the presence of free market structures within the olive oil production feeding the city of Rome.” What about the rest of the Roman empire? Rubio-Campillo, X. et al. In press. Bayesian analysis and free market trade within the Roman Empire, Antiquity .

Research questions Is there a relation between the distribution of amphoric stamps and the provincial structure?

Research questions Is there a relation between the distribution of amphoric stamps and the provincial structure? Q1: Do sites in the same province have similar stamps?

Research questions Is there a relation between the distribution of amphoric stamps and the provincial structure? Q1: Do sites in the same province have similar stamps? Q2: What provinces have similar stamps?

The distribution of amphoric stamps

Identifying province structure Idea: Two sites of the same province will have more similar stamps than two sites located at difgerent provinces

Identifying province structure Idea: Two sites of the same province will have more similar stamps than two sites located at difgerent provinces Null hypothesis There is no relation between the province of a site and its stamps

Identifying province structure We need to... ...quantify the similarity of stamps Null hypothesis There is no relation between the province of a site and its stamps

Identifying province structure We need to... ...quantify the similarity of stamps ...create a distance matrix of similarities between sites Null hypothesis There is no relation between the province of a site and its stamps

Identifying province structure We need to... ...quantify the similarity of stamps ...create a distance matrix of similarities between sites ...compare similarities within/between provinces Null hypothesis There is no relation between the province of a site and its stamps

Quantifying similarity We will use the Jaccard distance: 2 sites have exactly the same stamps → 0 2 sites have completely difgerent stamps 1 → PNN QCM VIRG SRN Emporiae 1 1 1 0 Massalia 1 1 1 1 Jaccard distance: 0.25 PNN QCM VIRG SRN Emporiae 1 1 1 0 Vindolanda 1 0 0 1 Jaccard distance: 0.75

Multi-Response Permutation Procedure MRPP allows us to assess if a specifjc grouping is linked to a dissimilarity matrix It evaluates statistical signifjcant difgerences between: the mean distance within each group the mean distance for the entire dataset weighted by group sizes McCune, B., & Grace, J. (2002). MRPP (Multi-response Permutation Procedures) and related techniques. Analysis of Ecological Communities: MjM Software Design, Gleneden Beach, Oregon, USA, 188–197. Rodgers, P. (1987). Multi-Response permutation procedures. Computer and Quantitative Methods in Archaeology, 7957, 45–54.

MRPP results Mean distances average within provinces 0.995 between provinces 0.997 Efgect 0.002 Signifjcance: 0.001

MRPP results Mean distances average within provinces 0.995 between provinces 0.997 Efgect 0.002 Signifjcance: 0.001

MRPP revisited P-value < 0.01 for all tests

MRPP revisited n=1 P-value < 0.01 for all tests

MRPP revisited n=25 P-value < 0.01 for all tests

MRPP revisited What provinces have similar stamps? n=25 P-value < 0.01 for all tests

Similarity between provinces 34

Similarity between provinces

Similarity between provinces

Discussion There is a relation between the province of a site and its stamps

Discussion There is a relation between the province of a site and its stamps Stamp similarity is linked to common boundaries

Discussion There is a relation between the province of a site and its stamps Stamp similarity is linked to common boundaries Exceptions can answer to political dynamics

Discussion There is a relation between the province of a site and its stamps Stamp similarity is linked to common boundaries Exceptions can answer to political dynamics Trade routes seem to emerge from province similarity

Concluding remarks The framework can test new hypotheses

Concluding remarks The framework can test new hypotheses Riverine transport Atlantic vs Mediterranean

Concluding remarks The framework can test new hypotheses Riverine transport Atlantic vs Mediterranean Independent military network

Concluding remarks The framework can test new hypotheses Riverine transport Atlantic vs Mediterranean Distribution of other goods Independent military network

Concluding remarks The framework can test new hypotheses Riverine transport Atlantic vs Mediterranean Distribution of other goods Independent military network A move from Descriptive statistics to Hypothesis Testing would improve our interpretations

Concluding remarks The framework can test new hypotheses Riverine transport Atlantic vs Mediterranean Distribution of other goods Independent military network A move from Descriptive statistics to Hypothesis Testing would improve our interpretations Any quantitative analysis should integrate the complexities of the archaeological record

Thank you! «Humans are pattern-seeking story-telling animals, and we are quite adept at telling stories about patterns, whether they exist or not» Michael Shermer Source code and dataset available at: https://github.com/xrubio/ecologyStamps @xrubiocampillo xavier.rubio@ed.ac.uk