diff --git a/backend/packages/Upgrade/src/api/DTO/ExperimentDTO.ts b/backend/packages/Upgrade/src/api/DTO/ExperimentDTO.ts
index 28a7b36c5f..c7a6e4b778 100644
--- a/backend/packages/Upgrade/src/api/DTO/ExperimentDTO.ts
+++ b/backend/packages/Upgrade/src/api/DTO/ExperimentDTO.ts
@@ -361,7 +361,7 @@ export class ExperimentDTO {
 
   @IsOptional()
   @IsEnum(ASSIGNMENT_ALGORITHM)
-  public assignmentAlgorithm: ASSIGNMENT_ALGORITHM;
+  public assignmentAlgorithm?: ASSIGNMENT_ALGORITHM;
 
   // TODO add conditional validity here ie endOn is null
   @IsOptional()
diff --git a/backend/packages/Upgrade/src/api/models/Experiment.ts b/backend/packages/Upgrade/src/api/models/Experiment.ts
index 80d18e0f16..2ccfecd5bf 100644
--- a/backend/packages/Upgrade/src/api/models/Experiment.ts
+++ b/backend/packages/Upgrade/src/api/models/Experiment.ts
@@ -113,6 +113,7 @@ export class Experiment extends BaseModel {
   @Column({
     type: 'enum',
     enum: ASSIGNMENT_ALGORITHM,
+    default: ASSIGNMENT_ALGORITHM.RANDOM,
   })
   public assignmentAlgorithm: ASSIGNMENT_ALGORITHM;