date reformatting

more justification for choices in reformatting the dating, thanks reviewer#2

Author: lsteinmann

inst/extdata/num_dating_edit.csv

@@ -3,7 +3,7 @@
 2,end of 1st c. BC – beg. of 1st c. AD,-20,20
 3,end 2nd c. BC,-120,-100
 4,early 1st c. AD,1,20
-7,after 212 AD,212,250
+7,after 212 AD,212,222
 8,AD 531,531,531
 10,5th/6th century AD,400,599
 14,3rd/4th century AD,200,399
@@ -45,7 +45,7 @@
 105,late 3rd century AD,280,299
 106,late 2nd century AD,180,199
 107,end of the 2nd/beg. of the 3rd century AD,180,220
-108,after 98 AD,98,120
+108,after 98 AD,98,108
 111,AD 209,209,209
 113,6th century AD,500,599
 114,5th - 6th century AD,400,599
@@ -58,7 +58,7 @@
 147,beg. of the 3rd c. AD,200,220
 148,beg. of the 2nd c. AD,100,120
 149,after ca. 70–79 AD,70,79
-150,after 128 AD,128,150
+150,after 128 AD,128,138
 152,AD 243/244,243,244
 154,97/98–98/99 AD,97,99
 158,5th/4th century BC,-499,-300
@@ -69,7 +69,7 @@
 183,1st century BC,-99,-1
 200,102–114,102,114
 201,early 3rd century AD,200,220
-203,after 138 AD,138,150
+203,after 138 AD,138,148
 207,3rd/4th century AD (or later),200,450
 208,3rd or 4th century AD,200,399
 209,3rd c. AD or before,180,299
@@ -80,17 +80,17 @@
 234,122/123–126/127 AD,122,127
 237,early 3rd c. AD,200,220
 238,ca. 2nd century AD,100,199
-239,before 212 AD,200,212
-240,before 211 AD,200,211
-241,after 202 AD,202,250
+239,before 212 AD,202,212
+240,before 211 AD,201,211
+241,after 202 AD,202,212
 259,mid – end of 3rd c. AD,240,299
 263,281 or 190 BC,-281,-190
 270,AD 288/289,288,289
 271,mid – end of 2nd c. AD,140,199
 272,late 2nd century AD ,180,199
 273,end of the 2nd – 3rd c. AD,180,299
 274,beg. of the 2nd c. BC,-200,-180
-275,"after 171 BC, ca. 188 BC",-188,-171
+275,"after 171 BC, ca. 188 BC",-188,-161
 279,7th century AD,600,699
 281,5th – 6th C AD,400,599
 283,4th – 6th c. AD,300,599

vignettes/data_preparation.Rmd

@@ -248,7 +248,7 @@ num_dating <- num_dating[which(is.na(num_dating$DAT_min)),]
 
 ### Reformatting of Imprecise Dating Values
 
-For dates that are around a certain value, i.e. of the format "ca. 190 AD", we decided to take a total span of 20 years, i.e. 10 years before and 10 years after the mentioned value. "ca. 190 AD" thus becomes "180--200 AD", with the same mechanism for BC in negative values.
+For dates that are around a certain value, i.e. of the format "ca. 190 AD", we are not able to make a more informed decision than guess about what the researchers providing this assessment had in mind. This might also change from inscription to inscription. While a closer look at the individual inscriptions may yield a more sensible estimate, this seems not feasible as part of the data preparation process. It seems that in most cases, if the dating can be as precise as a span of around 10 years, researchers tend to emphasize this. Therefore we decided to take a total span of 20 years, i.e. 10 years before and 10 years after the mentioned value, reflecting some uncertainty on the precision and duration of the estimate. "ca. 190 AD" thus becomes "180--200 AD", with the same mechanism for BC in negative values.
 
 
 ```{r }
@@ -281,7 +281,7 @@ num_dating <- num_dating[which(is.na(num_dating$DAT_min)),]
 unique(num_dating$Dating)[1:20]
 ```
 
-Due to the heterogeneous nature of these `r nrow(num_dating)` values, we decided to convert them manually again. Our criteria for translating terms like "beginning of" are the following: "beginning of", "end of", "early", "late" all translate to 20 years, as we assume that more information would have been given if the time span was greater than a quarter century. For the other values, we employed the same criteria as seen above in the automated process. For another transformation used later on we decided to treat e.g. -199 / 100 as the beginning of century, and e.g. -100 / 199 as the end of the century and did so accordingly in the manual assignment. 
+Due to the heterogeneous nature of these `r nrow(num_dating)` values, we decided to convert them manually again. Our criteria for translating terms like "beginning of" are the following: "beginning of", "end of", "early", "late" are -- similarly to ca. -- all translated to 20 years, as we assume that more information would have been given if the time span was greater than a quarter century. For the other values, we employed the same criteria as seen above in the automated process. For another transformation used later on we decided to treat e.g. -199 / 100 as the beginning of century, and e.g. -100 / 199 as the end of the century and did so accordingly in the manual assignment. Since the data is epigraphical, in the case of "before" or "after" (i.e. terminus ante/post quem) dates, we assume some connection to a datable event, and therefore add or subtract a span of 10 years, which is, however, still rather arbitrary. 
 
 As a last step, we switch the in some cases automatically assigned year 0, so that it will be treated as either 1 oder -1:
 ```{r}