diff --git a/simple/sample/output/debug/observations.csv b/simple/sample/output/debug/observations.csv
index baebe2a0..c5c9b240 100644
--- a/simple/sample/output/debug/observations.csv
+++ b/simple/sample/output/debug/observations.csv
@@ -21,10 +21,10 @@ country/ASM,var2,2023,34,c/p/1
 country/AIA,var2,2023,42,c/p/1
 country/WLF,var2,2023,75,c/p/1
 country/ESH,var2,2023,65,c/p/1
-geoId/01,custom/statvar_1,2021,555,c/p/1
-geoId/122,custom/statvar_1,2022,321,c/p/1
-geoId/01,custom/statvar_2,2021,666,c/p/1
-geoId/122,custom/statvar_2,2022,123456,c/p/1
+geoId/01,Variable_1,2021,555,c/p/1
+geoId/122,Variable_1,2022,321,c/p/1
+geoId/01,Variable_2,2021,666,c/p/1
+geoId/122,Variable_2,2022,123456,c/p/1
 country/USA,var1,2021,555,c/p/1
 country/IND,var1,2022,321,c/p/1
 country/USA,var2,2021,666,c/p/1
diff --git a/simple/sample/output/debug/triples.csv b/simple/sample/output/debug/triples.csv
index 5dff3759..1c01d0ea 100644
--- a/simple/sample/output/debug/triples.csv
+++ b/simple/sample/output/debug/triples.csv
@@ -51,16 +51,16 @@ var2,memberOf,custom/g/group_3,""
 var2,includedIn,c/p/1,""
 var2,includedIn,c/p/2,""
 var2,includedIn,c/s/1,""
-custom/statvar_1,typeOf,StatisticalVariable,""
-custom/statvar_1,name,"","Variable 1"
-custom/statvar_1,memberOf,custom/g/group_1,""
-custom/statvar_1,includedIn,c/p/1,""
-custom/statvar_1,includedIn,c/s/1,""
-custom/statvar_2,typeOf,StatisticalVariable,""
-custom/statvar_2,name,"","Variable 2"
-custom/statvar_2,memberOf,custom/g/Root,""
-custom/statvar_2,includedIn,c/p/1,""
-custom/statvar_2,includedIn,c/s/1,""
+Variable_1,typeOf,StatisticalVariable,""
+Variable_1,name,"","Variable 1"
+Variable_1,memberOf,custom/g/group_1,""
+Variable_1,includedIn,c/p/1,""
+Variable_1,includedIn,c/s/1,""
+Variable_2,typeOf,StatisticalVariable,""
+Variable_2,name,"","Variable 2"
+Variable_2,memberOf,custom/g/Root,""
+Variable_2,includedIn,c/p/1,""
+Variable_2,includedIn,c/s/1,""
 country/AFG,typeOf,Country,""
 country/YEM,typeOf,Country,""
 country/AGO,typeOf,Country,""
diff --git a/simple/sample/output/nl/sentences.csv b/simple/sample/output/nl/sentences.csv
index 1ae6188d..0f148100 100644
--- a/simple/sample/output/nl/sentences.csv
+++ b/simple/sample/output/nl/sentences.csv
@@ -1,5 +1,5 @@
 dcid,sentence
 var1,Good var1 name;Good var1 description;Natural language sentence 1;Natural language sentence 2
 var2,Good var2 name
-custom/statvar_1,Variable 1
-custom/statvar_2,Variable 2
+Variable_1,Variable 1
+Variable_2,Variable 2
diff --git a/simple/sample/output/triples.csv b/simple/sample/output/triples.csv
index 88085c8a..d2611fe9 100644
--- a/simple/sample/output/triples.csv
+++ b/simple/sample/output/triples.csv
@@ -51,16 +51,16 @@ var2,memberOf,custom/g/group_3,
 var2,includedIn,c/p/1,
 var2,includedIn,c/p/2,
 var2,includedIn,c/s/1,
-custom/statvar_1,typeOf,StatisticalVariable,
-custom/statvar_1,name,,Variable 1
-custom/statvar_1,memberOf,custom/g/group_1,
-custom/statvar_1,includedIn,c/p/1,
-custom/statvar_1,includedIn,c/s/1,
-custom/statvar_2,typeOf,StatisticalVariable,
-custom/statvar_2,name,,Variable 2
-custom/statvar_2,memberOf,custom/g/Root,
-custom/statvar_2,includedIn,c/p/1,
-custom/statvar_2,includedIn,c/s/1,
+Variable_1,typeOf,StatisticalVariable,
+Variable_1,name,,Variable 1
+Variable_1,memberOf,custom/g/group_1,
+Variable_1,includedIn,c/p/1,
+Variable_1,includedIn,c/s/1,
+Variable_2,typeOf,StatisticalVariable,
+Variable_2,name,,Variable 2
+Variable_2,memberOf,custom/g/Root,
+Variable_2,includedIn,c/p/1,
+Variable_2,includedIn,c/s/1,
 country/AFG,typeOf,Country,
 country/YEM,typeOf,Country,
 country/AGO,typeOf,Country,
diff --git a/simple/stats/config.py b/simple/stats/config.py
index 6ee62f7e..8449ca50 100644
--- a/simple/stats/config.py
+++ b/simple/stats/config.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from stats.data import AggregationConfig
 from stats.data import EventType
 from stats.data import ImportType
 from stats.data import Provenance
@@ -35,6 +36,8 @@
 _EVENT_TYPE_FIELD = "eventType"
 _ID_COLUMN_FIELD = "idColumn"
 _EVENTS_FIELD = "events"
+_COMPUTED_VARIABLES_FIELD = "computedVariables"
+_AGGREGATION_FIELD = "aggregation"
 
 
 class Config:
@@ -60,6 +63,9 @@ def import_type(self, input_file_name: str) -> ImportType:
           f"Unsupported import type: {import_type_str} ({input_file_name})")
     return ImportType(import_type_str)
 
+  def computed_variables(self, input_file_name: str) -> list[str]:
+    return self._input_file(input_file_name).get(_COMPUTED_VARIABLES_FIELD, [])
+
   def variable(self, variable_name: str) -> StatVar:
     var_cfg = self.data.get(_VARIABLES_FIELD, {}).get(variable_name, {})
     return StatVar(
@@ -70,6 +76,12 @@ def variable(self, variable_name: str) -> StatVar:
         group_path=var_cfg.get(_GROUP_FIELD, ""),
     )
 
+  def aggregation(self, variable_name: str) -> AggregationConfig:
+    aggregation_cfg = self.data.get(_VARIABLES_FIELD, {}) \
+      .get(variable_name, {}) \
+      .get(_AGGREGATION_FIELD, {})
+    return AggregationConfig(**aggregation_cfg)
+
   def event_type(self, input_file_name: str) -> str:
     return self._input_file(input_file_name).get(_EVENT_TYPE_FIELD, "")
 
diff --git a/simple/stats/data.py b/simple/stats/data.py
index a7cca4e4..55837d8e 100644
--- a/simple/stats/data.py
+++ b/simple/stats/data.py
@@ -267,3 +267,25 @@ def triples(self) -> list[Triple]:
 class ImportType(StrEnum):
   OBSERVATIONS = "observations"
   EVENTS = "events"
+
+
+class TimePeriod(StrEnum):
+  DAY = "day"
+  MONTH = "month"
+  YEAR = "year"
+
+
+class AggregationMethod(StrEnum):
+  COUNT = "count"
+
+
+@dataclass
+class AggregationConfig:
+  period: TimePeriod = TimePeriod.YEAR
+  method: AggregationMethod = AggregationMethod.COUNT
+
+  def __post_init__(self):
+    if self.period not in TimePeriod._member_map_.values():
+      raise ValueError(f"invalid period: {self.period}")
+    if self.method not in AggregationMethod._member_map_.values():
+      raise ValueError(f"invalid method: {self.method}")
diff --git a/simple/stats/events_importer.py b/simple/stats/events_importer.py
index d78c10aa..95f9b7ef 100644
--- a/simple/stats/events_importer.py
+++ b/simple/stats/events_importer.py
@@ -12,12 +12,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from datetime import datetime
 import logging
 import random
 
+from dateutil.parser import parse as date_parse
 import pandas as pd
 from stats import constants
+from stats.data import AggregationConfig
+from stats.data import AggregationMethod
 from stats.data import Event
+from stats.data import Observation
+from stats.data import TimePeriod
 from stats.data import Triple
 from stats.db import Db
 from stats.importer import Importer
@@ -65,7 +71,6 @@ def do_import(self) -> None:
       self._drop_ignored_columns()
       self._sanitize_values()
       self._resolve_entities()
-      self._parse_dates()
       self._rename_columns()
       self._write_event_triples()
       self._write_observations()
@@ -115,13 +120,50 @@ def _rename_columns(self) -> None:
 
     self.df = self.df.rename(columns=renamed)
 
-  def _parse_dates(self) -> None:
-    # TODO: parse dates and update value if needed (e.g. year, month, day).
-    pass
-
   def _write_observations(self) -> None:
-    # TODO: compute aggregated observations and insert in DB.
-    pass
+    sv_names = self.config.computed_variables(self.input_file_name)
+    if not sv_names:
+      logging.warning("No computed variables specified: %s",
+                      self.input_file_name)
+      return
+
+    for sv_name in sv_names:
+      sv_dcid = self.nodes.variable(sv_name, self.input_file_name).id
+      aggr_cfg = self.config.aggregation(sv_name)
+      observations = self._compute_sv_observations(sv_dcid, aggr_cfg)
+      self.db.insert_observations(observations)
+
+  def _compute_sv_observations(
+      self, sv_dcid: str, aggr_cfg: AggregationConfig = AggregationConfig()
+  ) -> list[Observation]:
+    # Create df with only dcid and date columns.
+    obs_df = self.df.loc[:, [constants.COLUMN_DCID, constants.COLUMN_DATE]]
+
+    # Convert date to aggregation period
+    obs_df[constants.COLUMN_DATE] = obs_df[constants.COLUMN_DATE].apply(
+        lambda x: _time_period(x, aggr_cfg.period))
+
+    # Group by entity (dcid) and date, count each group and drop duplicates.
+    # NOTE: currently we only support count per entity and date.
+    # The groupby columns and transform functions will need to change
+    # when we add support for more aggregation methods (sum, average, etc.)
+    obs_df[constants.COLUMN_VALUE] = obs_df.groupby(
+        [constants.COLUMN_DCID,
+         constants.COLUMN_DATE])[constants.COLUMN_DCID].transform("count")
+    obs_df.drop_duplicates(inplace=True, ignore_index=True)
+
+    # Add variable and provenance columns.
+    obs_df[constants.COLUMN_VARIABLE] = sv_dcid
+    obs_df[constants.COLUMN_PROVENANCE] = self.provenance
+
+    # Reorder columns so they are in the same order as observations
+    obs_df = obs_df.reindex(columns=[
+        constants.COLUMN_DCID, constants.COLUMN_VARIABLE, constants.COLUMN_DATE,
+        constants.COLUMN_VALUE, constants.COLUMN_PROVENANCE
+    ])
+
+    # Map each row to an Observation object and return the list of observations.
+    return [Observation(*row) for row in obs_df.itertuples(index=False)]
 
   def _write_event_triples(self) -> None:
     # Add event type node - it will be written to DB later.
@@ -259,3 +301,14 @@ def _write_debug_csvs(self) -> None:
                    self.debug_resolve_fh)
       self.debug_resolve_fh.write_string(
           self.debug_resolve_df.to_csv(index=False))
+
+
+# Utility methods
+def _time_period(date_str: str, period: TimePeriod) -> str:
+  date = date_parse(date_str)
+  if period == TimePeriod.DAY:
+    return date.strftime("%Y-%m-%d")
+  if period == TimePeriod.YEAR:
+    return date.strftime("%Y")
+  # Default to month
+  return date.strftime("%Y-%m")
diff --git a/simple/stats/nodes.py b/simple/stats/nodes.py
index c0f39ffa..20f8fdcd 100644
--- a/simple/stats/nodes.py
+++ b/simple/stats/nodes.py
@@ -159,8 +159,14 @@ def _add_provenance(self, sv: StatVar, provenance: Provenance) -> StatVar:
     return sv
 
   def _sv_id(self, sv_column_name: str) -> str:
-    if re.fullmatch(_DCID_PATTERN, sv_column_name):
-      return sv_column_name
+    dcid = sv_column_name
+    if re.fullmatch(_DCID_PATTERN, dcid):
+      return dcid
+    # Convert spaces and dashes to underscores and check if that
+    # is a valid DCID pattern
+    dcid = re.sub(r"[ -]", "_", dcid)
+    if re.fullmatch(_DCID_PATTERN, dcid):
+      return dcid
     self._sv_generated_id_count += 1
     return f"{_CUSTOM_SV_ID_PREFIX}{self._sv_generated_id_count}"
 
diff --git a/simple/tests/stats/config_test.py b/simple/tests/stats/config_test.py
index 5ba84c01..1f24c8f4 100644
--- a/simple/tests/stats/config_test.py
+++ b/simple/tests/stats/config_test.py
@@ -15,10 +15,13 @@
 import unittest
 
 from stats.config import Config
+from stats.data import AggregationConfig
+from stats.data import AggregationMethod
 from stats.data import ImportType
 from stats.data import Provenance
 from stats.data import Source
 from stats.data import StatVar
+from stats.data import TimePeriod
 
 CONFIG_DATA = {
     "inputFiles": {
@@ -42,10 +45,18 @@
     },
     "variables": {
         "Variable 1": {
-            "group": "Parent Group/Child Group 1"
+            "group": "Parent Group/Child Group 1",
+            "aggregation": {
+                "period": "month",
+                "method": "count"
+            }
         },
         "Variable 2": {
-            "group": "Parent Group/Child Group 1"
+            "group": "Parent Group/Child Group 1",
+            "aggregation": {
+                "period": "INVALID",
+                "method": "count"
+            }
         },
         "var3": {
             "name": "Var 3 Name",
@@ -170,6 +181,19 @@ def test_import_type(self):
     with self.assertRaisesRegex(ValueError, "Unsupported import type"):
       config.import_type("invalid_import_type.csv")
 
+  def test_aggregation(self):
+    config = Config(CONFIG_DATA)
+    self.assertEqual(
+        config.aggregation("Variable 1"),
+        AggregationConfig(TimePeriod.MONTH, AggregationMethod.COUNT),
+        "valid date config")
+    self.assertEqual(
+        config.aggregation("var3"),
+        AggregationConfig(TimePeriod.YEAR, AggregationMethod.COUNT),
+        "default date config")
+    with self.assertRaisesRegex(ValueError, "invalid period"):
+      config.aggregation("Variable 2")
+
   def test_empty_config(self):
     config = Config({})
     self.assertEqual(config.variable("Variable 1"), StatVar("", "Variable 1"))
diff --git a/simple/tests/stats/nodes_test.py b/simple/tests/stats/nodes_test.py
index fe1011a9..76517dd9 100644
--- a/simple/tests/stats/nodes_test.py
+++ b/simple/tests/stats/nodes_test.py
@@ -139,7 +139,7 @@ def test_variable_with_no_config(self):
     self.assertEqual(
         sv,
         StatVar(
-            "custom/statvar_1",
+            "Variable_with_no_config",
             "Variable with no config",
             group_id="custom/g/Root",
             provenance_ids=["c/p/1"],
@@ -169,7 +169,7 @@ def test_variable_with_group(self):
     self.assertEqual(
         sv,
         StatVar(
-            "custom/statvar_1",
+            "Variable_1",
             "Variable 1",
             group_id="custom/g/group_2",
             provenance_ids=["c/p/1"],
@@ -202,7 +202,7 @@ def test_multiple_variables_in_same_group(self):
     self.assertEqual(
         sv,
         StatVar(
-            "custom/statvar_1",
+            "Variable_1",
             "Variable 1",
             group_id="custom/g/group_2",
             provenance_ids=["c/p/1"],
@@ -213,7 +213,7 @@ def test_multiple_variables_in_same_group(self):
     self.assertEqual(
         sv,
         StatVar(
-            "custom/statvar_2",
+            "Variable_2",
             "Variable 2",
             group_id="custom/g/group_2",
             provenance_ids=["c/p/1"],
diff --git a/simple/tests/stats/test_data/events_importer/expected/countryalpha3codes.observations.db.csv b/simple/tests/stats/test_data/events_importer/expected/countryalpha3codes.observations.db.csv
index 8b137891..4e678908 100644
--- a/simple/tests/stats/test_data/events_importer/expected/countryalpha3codes.observations.db.csv
+++ b/simple/tests/stats/test_data/events_importer/expected/countryalpha3codes.observations.db.csv
@@ -1 +1,4 @@
-
+entity,variable,date,value,provenance
+country/USA,Count_CrimeEvent,2023,3,c/p/1
+country/BRA,Count_CrimeEvent,2023,2,c/p/1
+country/CHN,Count_CrimeEvent,2023,2,c/p/1
diff --git a/simple/tests/stats/test_data/events_importer/expected/countryalpha3codes.triples.db.csv b/simple/tests/stats/test_data/events_importer/expected/countryalpha3codes.triples.db.csv
index 0eb5278d..87fc661b 100644
--- a/simple/tests/stats/test_data/events_importer/expected/countryalpha3codes.triples.db.csv
+++ b/simple/tests/stats/test_data/events_importer/expected/countryalpha3codes.triples.db.csv
@@ -237,6 +237,14 @@ c/p/1,typeOf,Provenance,
 c/p/1,name,,Test Provenance
 c/p/1,source,c/s/1,
 c/p/1,url,,http://source.com/provenance
+custom/g/Root,typeOf,StatVarGroup,
+custom/g/Root,name,,Custom Variables
+custom/g/Root,specializationOf,dc/g/Root,
+Count_CrimeEvent,typeOf,StatisticalVariable,
+Count_CrimeEvent,name,,Count_CrimeEvent
+Count_CrimeEvent,memberOf,custom/g/Root,
+Count_CrimeEvent,includedIn,c/p/1,
+Count_CrimeEvent,includedIn,c/s/1,
 CrimeEvent,typeOf,Class,
 CrimeEvent,subClassOf,Event,
 CrimeEvent,name,,Crime Event
diff --git a/simple/tests/stats/test_data/events_importer/expected/idcolumns.observations.db.csv b/simple/tests/stats/test_data/events_importer/expected/idcolumns.observations.db.csv
index 8b137891..07363c24 100644
--- a/simple/tests/stats/test_data/events_importer/expected/idcolumns.observations.db.csv
+++ b/simple/tests/stats/test_data/events_importer/expected/idcolumns.observations.db.csv
@@ -1 +1,6 @@
-
+entity,variable,date,value,provenance
+country/USA,Crime_Event2_Count,2023-11-08,2,c/p/1
+country/BRA,Crime_Event2_Count,2023-11-08,2,c/p/1
+country/CHN,Crime_Event2_Count,2023-11-08,1,c/p/1
+country/CHN,Crime_Event2_Count,2023-09-17,1,c/p/1
+country/USA,Crime_Event2_Count,2023-08-02,1,c/p/1
diff --git a/simple/tests/stats/test_data/events_importer/expected/idcolumns.triples.db.csv b/simple/tests/stats/test_data/events_importer/expected/idcolumns.triples.db.csv
index cf696f65..85cd0dde 100644
--- a/simple/tests/stats/test_data/events_importer/expected/idcolumns.triples.db.csv
+++ b/simple/tests/stats/test_data/events_importer/expected/idcolumns.triples.db.csv
@@ -237,6 +237,14 @@ c/p/1,typeOf,Provenance,
 c/p/1,name,,Test Provenance
 c/p/1,source,c/s/1,
 c/p/1,url,,http://source.com/provenance
+custom/g/Root,typeOf,StatVarGroup,
+custom/g/Root,name,,Custom Variables
+custom/g/Root,specializationOf,dc/g/Root,
+Crime_Event2_Count,typeOf,StatisticalVariable,
+Crime_Event2_Count,name,,Number of Crime2 Events
+Crime_Event2_Count,memberOf,custom/g/Root,
+Crime_Event2_Count,includedIn,c/p/1,
+Crime_Event2_Count,includedIn,c/s/1,
 CrimeEvent2,typeOf,Class,
 CrimeEvent2,subClassOf,Event,
 CrimeEvent2,name,,CrimeEvent2
diff --git a/simple/tests/stats/test_data/events_importer/input/config.json b/simple/tests/stats/test_data/events_importer/input/config.json
index c043372d..e92f14c8 100644
--- a/simple/tests/stats/test_data/events_importer/input/config.json
+++ b/simple/tests/stats/test_data/events_importer/input/config.json
@@ -3,13 +3,15 @@
     "countryalpha3codes.csv": {
       "eventType": "CrimeEvent",
       "entityType": "Country",
-      "provenance": "Test Provenance"
+      "provenance": "Test Provenance",
+      "computedVariables": ["Count_CrimeEvent"]
     },
     "idcolumns.csv": {
       "eventType": "CrimeEvent2",
       "entityType": "Country",
       "provenance": "Test Provenance",
-      "idColumn": "CASE"
+      "idColumn": "CASE",
+      "computedVariables": ["Crime Event2 Count"]
     }
   },
   "events": {
@@ -18,6 +20,14 @@
       "description": "Crime Event description"
     }
   },
+  "variables": {
+    "Crime Event2 Count": {
+      "name": "Number of Crime2 Events",
+      "aggregation": {
+        "period": "day"
+      }
+    }
+  },
   "sources": {
     "Test Source": {
       "url": "http://source.com",
diff --git a/simple/tests/stats/test_data/nodes/expected/triples.csv b/simple/tests/stats/test_data/nodes/expected/triples.csv
index 4ff30b47..37914998 100644
--- a/simple/tests/stats/test_data/nodes/expected/triples.csv
+++ b/simple/tests/stats/test_data/nodes/expected/triples.csv
@@ -33,27 +33,27 @@ custom/g/group_3,includedIn,c/s/default,
 custom/g/Root,typeOf,StatVarGroup,
 custom/g/Root,name,,Custom Variables
 custom/g/Root,specializationOf,dc/g/Root,
-custom/statvar_1,typeOf,StatisticalVariable,
-custom/statvar_1,name,,Variable 1
-custom/statvar_1,memberOf,custom/g/group_2,
-custom/statvar_1,includedIn,c/p/1,
-custom/statvar_1,includedIn,c/s/1,
-custom/statvar_2,typeOf,StatisticalVariable,
-custom/statvar_2,name,,Variable 2
-custom/statvar_2,memberOf,custom/g/group_2,
-custom/statvar_2,includedIn,c/p/1,
-custom/statvar_2,includedIn,c/s/1,
+Variable_1,typeOf,StatisticalVariable,
+Variable_1,name,,Variable 1
+Variable_1,memberOf,custom/g/group_2,
+Variable_1,includedIn,c/p/1,
+Variable_1,includedIn,c/s/1,
+Variable_2,typeOf,StatisticalVariable,
+Variable_2,name,,Variable 2
+Variable_2,memberOf,custom/g/group_2,
+Variable_2,includedIn,c/p/1,
+Variable_2,includedIn,c/s/1,
 var3,typeOf,StatisticalVariable,
 var3,name,,Var 3 Name
 var3,description,,Var 3 Description
 var3,memberOf,custom/g/group_3,
 var3,includedIn,c/p/default,
 var3,includedIn,c/s/default,
-custom/statvar_3,typeOf,StatisticalVariable,
-custom/statvar_3,name,,Variable with no config
-custom/statvar_3,memberOf,custom/g/Root,
-custom/statvar_3,includedIn,c/p/default,
-custom/statvar_3,includedIn,c/s/default,
+Variable_with_no_config,typeOf,StatisticalVariable,
+Variable_with_no_config,name,,Variable with no config
+Variable_with_no_config,memberOf,custom/g/Root,
+Variable_with_no_config,includedIn,c/p/default,
+Variable_with_no_config,includedIn,c/s/default,
 CrimeEvent,typeOf,Class,
 CrimeEvent,subClassOf,Event,
 CrimeEvent,name,,Crime Event