diff --git a/datasets/raise/split_and_compare_prnus_of_subgroups.py b/datasets/raise/split_and_compare_prnus_of_subgroups.py
index d3e77c4..6cfe99e 100644
--- a/datasets/raise/split_and_compare_prnus_of_subgroups.py
+++ b/datasets/raise/split_and_compare_prnus_of_subgroups.py
@@ -6,6 +6,7 @@ from utils import denoise
 from skimage import img_as_float
 import sys
 import os
+from random import shuffle
 
 sys.path.insert(0, '../../algorithms/distance/')
 
@@ -16,10 +17,11 @@ DENOISER = 'wavelet'
 IMAGES_FOLDER = 'flat-field/TIF'
 
 imagesFileNames = os.listdir(IMAGES_FOLDER)
+# To not have a bias (chronological for instance) when split to make subgroups.
+shuffle(imagesFileNames)
 numberOfImagesPerSubgroup = len(imagesFileNames) // NUMBER_OF_SUBGROUPS
 numberOfImagesThresholds = range(numberOfImagesPerSubgroup, numberOfImagesPerSubgroup + 1)
 
-# Assume random image order to not introduce a bias.
 subgroupsPrnuEstimatesNpArray = []
 for subgroupIndex in tqdm(range(NUMBER_OF_SUBGROUPS), 'Subgroup'):
     imagesPrnuEstimateNpArray = []