I'm looking at the Penn World Table 9.0 data, and find that the "Share of merchandise imports at current PPPs" (csh_m
) can be negative. For example,
country year csh_m
<chr> <dbl> <dbl>
1 Aruba 1970. -0.485
2 Aruba 1971. -0.459
3 Aruba 1972. -0.436
4 Aruba 1973. -0.441
My initial thought is that the share of import (csh_m
) here actually means "net import as share of GDP." However, this is not correct, because share of import (csh_m
) and share of export (csh_x
) don't have the same magnitude.
country year csh_m csh_x
<chr> <dbl> <dbl> <dbl>
1 Aruba 1970. -0.485 0.427
2 Aruba 1971. -0.459 0.435
3 Aruba 1972. -0.436 0.441
4 Aruba 1973. -0.441 0.477
Where can I find documentation explaining the construction of
csh_m
andcsh_x
from the Penn World Table?If a want to construct a variable of trade openness, should I add the absolute values of
csh_m
andcsh_x
?
csh_m
(Share of merchandise imports at current PPPs) numbers in that table for all years and all countries are negative (apart from some years for Bermuda) while allcsh_x
(Share of merchandise exports at current PPPs) are positive (again except for a few years for Bermuda). These shares look like $Y=C+I+G+X-M+R$ all divided by $Y$. Places with big absolute values seem to include Hong Kong, Singapore, BVI, Malta, Turks & Caicos, where trade is indeed open. So you could add the absolute numbers together $\endgroup$