sdcLog options

Example data

We create a tiny data.frame to demonstrate the effects of the options:

library(sdcLog)
df <- data.frame(id = LETTERS[1:3], v1 = 1L:3L, v2 = c(1L, 2L, 4L))
df
#   id v1 v2
# 1  A  1  1
# 2  B  2  2
# 3  C  3  4

sdc.n_ids

By default, sdcLog expects at least five different entities behind each calculated number. The functions in sdcLog derive this number from getOption("sdc.n_ids", default = 5). That is, if the option sdc.n_ids is not set, it defaults to 5. Consider the following example:

sdc_descriptives(data = df, id_var = "id", val_var = "v1")
# Warning: Potential disclosure problem: Not enough distinct entities.
# [ OPTIONS:  sdc.n_ids: 5 | sdc.n_ids_dominance: 2 | sdc.share_dominance: 0.85 ]
# [ SETTINGS: id_var: id | val_var: v1 | zero_as_NA: FALSE ]
# Not enough distinct entities:
#    distinct_ids
# 1:            3

This can be adapted to the policy of your research data center by setting the option sdc.n_ids to the desired value. For example, if your policy allows results to be released if there are at least three different entities behind each number, set

options(sdc.n_ids = 3)

Now, getOption("sdc.n_ids", default = 5) evaluates to 3 and warnings are thrown only if there are less than three entities behind each result. Note that this is reflected in the first line of output from every function of sdcLog:

sdc_descriptives(data = df, id_var = "id", val_var = "v1")
# [ OPTIONS:  sdc.n_ids: 3 | sdc.n_ids_dominance: 2 | sdc.share_dominance: 0.85 ]
# [ SETTINGS: id_var: id | val_var: v1 | zero_as_NA: FALSE ]
# Output complies to RDC rules.

sdc.n_ids_dominance

The default value for sdc.n_ids_dominance is 2. In our example, this leads to a warning:

sdc_descriptives(data = df, id_var = "id", val_var = "v2")
# Warning: Potential disclosure problem: Dominant entities.
# [ OPTIONS:  sdc.n_ids: 3 | sdc.n_ids_dominance: 2 | sdc.share_dominance: 0.85 ]
# [ SETTINGS: id_var: id | val_var: v2 | zero_as_NA: FALSE ]
# Dominant entities:
#    value_share
# 1:   0.8571429

If your policy requires only the largest entity alone to attribute for a share of less than 0.85, set

options(sdc.n_ids_dominance = 1)

Then, there is no problem in the example:

sdc_descriptives(data = df, id_var = "id", val_var = "v2")
# [ OPTIONS:  sdc.n_ids: 3 | sdc.n_ids_dominance: 1 | sdc.share_dominance: 0.85 ]
# [ SETTINGS: id_var: id | val_var: v2 | zero_as_NA: FALSE ]
# Output complies to RDC rules.

sdc.share_dominance

The last option of sdcLog which affects internal calculations is sdc.share_dominance. To demonstrate, we first reset sdc.n_dominance to it’s default value of 2.

Let’s consider a policy which allows the largest two entities to attribute for a share of 0.8. To reflect this, set

options(sdc.share_dominance = 0.8)

Now, the initial example from sdc.n_ids throws a warning:

sdc_descriptives(data = df, id_var = "id", val_var = "v1")
# Warning: Potential disclosure problem: Dominant entities.
# [ OPTIONS:  sdc.n_ids: 3 | sdc.n_ids_dominance: 2 | sdc.share_dominance: 0.8 ]
# [ SETTINGS: id_var: id | val_var: v1 | zero_as_NA: FALSE ]
# Dominant entities:
#    value_share
# 1:   0.8333333

sdc.info_level

This option differs from the previous ones in the sense that is does not affect actual calculations. Instead, it determines the verbosity of the output of sdcLog functions. Possible values are 0, 1 (default), and 2. Before demonstrating the effects of sdc.info_level, we reset sdc.share_dominance to it’s default value of 0.85.

The example below shows the different levels of information printed to the console based on the different levels of sdc.info_level:

for (i in 0:2) {
  options(sdc.info_level = i)
  cat("\nsdc.info_level: ", getOption("sdc.info_level"), "\n")
  print(sdc_descriptives(data = df, id_var = "id", val_var = "v1"))
}
# 
# sdc.info_level:  0
# [ OPTIONS:  sdc.n_ids: 3 | sdc.n_ids_dominance: 2 | sdc.share_dominance: 0.85 ]
# [ SETTINGS: id_var: id | val_var: v1 | zero_as_NA: FALSE ]
# 
# sdc.info_level:  1
# [ OPTIONS:  sdc.n_ids: 3 | sdc.n_ids_dominance: 2 | sdc.share_dominance: 0.85 ]
# [ SETTINGS: id_var: id | val_var: v1 | zero_as_NA: FALSE ]
# Output complies to RDC rules.
# 
# sdc.info_level:  2
# [ OPTIONS:  sdc.n_ids: 3 | sdc.n_ids_dominance: 2 | sdc.share_dominance: 0.85 ]
# [ SETTINGS: id_var: id | val_var: v1 | zero_as_NA: FALSE ]
# No problem with number of distinct entities.
# No problem with dominance.
# Output complies to RDC rules.

At level 0, only options and settings are printed. Level 1 also prints a short message about the overall outcome of the checks. Level 2 additionally prints the results of the separate checks on distinct entities and dominance.

General remarks

Please note that these options affect all functions of sdcLog, not just sdc_descriptives().