Statistics

This section describes DNAvi’s statistical analyses and outputs.

Basic statistics

This table is a broad description of your dataset, specifically all numerical data provided.

Example of basic statistics output

sample

Skewness

Entropy

AUC

Sample_1

-0.506815236748803

5.82798573207947

1887.20275909115

Sample_2

-0.397997767576633

5.78724522789374

1873.61515282988

Sample_3

0.0450158293194279

5.81663576539858

2153.11636771802

Sample_4

1.51560919314785

5.77731789999923

853.845586533094
The following metrics are provided and exemplified based on the “bp_pos” column:

  • Skewness - skew of the size distribution, ~ 0 for normally distributed data

  • Entropy - Shannon entropy of the distribution

  • AUC - total area under the signal intensity curve

Peak statistics

This table contains information on average sizes and individual peaks. Let’s have a look at the line plots for two samples to understand the corresponding statistics:

Example stats
Example of peak statistics output

sample

region_id

From [bp]

To [bp]

AUC

value

unit

CONDITION

Sample_1

Mononucleosomal (100-200 bp)

100

200

73.8961612203105

10.6

percent total DNA (%)

Control

Sample_1

Dinucleosomal (201-400 bp)

201

400

115.647800412261

15

percent total DNA (%)

Control

Sample_1

modal_size

1282.6

bp

Control

Sample_1

median_size

820.7

bp

Control

Sample_1

average_size

962.91

bp

Control

Sample_1

likely gDNA (>3.5kB)

3501

0

0

percent total DNA (%)

Control

…

…

…

…

…

…

…

…

Sample_2

Mononucleosomal (100-200 bp)

100

200

72.414924632541

11.5

percent total DNA (%)

Treat

Rationale for adding peaks to the statistical evaluation (beyond nucleosomal fractions):

Our rationale is to catch the rare cases in which for example profiles are compared across species with larger nucleosomal differences,e.g. if the user defined the mononucleosomal interval from 100-200 bp but species A’s mononucleosomal peak is at 140 bp and species B’s mononucleosomal peak is at 210 bp. In this case, DNAvi reports there is a lower mononucleosomal fraction in B, which is technically true but biologically not correct. Since both peaks would be the first peaks in their respective sample (peak # 0) DNAvi would still compare them against each other.

List of metrics:

For each sample, these metrics are provided:

  • average_size : the average fragment size in bp, estimated from the signal table (histogram)

  • median_size : the median in bp, estimated from the signal table (histogram)

  • mode : the mode value in bp, estimated from the signal table (histogram)

  • max_peak: the most intense peak (peak with highest fluorescent signal) of this sample

  • metadata: additional columns assigning categories if Metadata were provided

  • peak_id: the detected peaks (0-based) for each sample, numbered from low to high fragment size, and their metrics. In the example, 6 peaks are detected in Sample_1 while 7 peaks detected in Sample_2.

  • a variety of nucleosomal fractions : the percentage of cfDNA in specific size intervals. Customizable!

  • estimated genomic DNA content : the percentage of estimated gDNA (based on high molecular weight DNA thresholds). Customizable!

Group statistics

For each variable specified in the Metadata a table containing statistical testing results is provided. Let’s have a look at an example where cell-free DNA from two groups (Control vs. Treatment) were compared. The metadata-based evaluation allows to answer biological questions (see also next section).

Note: DNAvi will choose the statistical test based on your group data distribution, by doing different tests:

  • Shapiro-Wilk test (can the hypothesis of a normal distribution be rejected),

  • Levene test (can we assume all input samples are from populations with equal variances)

  • Group size determination (2 or more)

Example stats
Example of group statistics output I

peak_name

test_performed

p_value

p<0.05

posthoc_p_values

unique_peak

average

modal

median

groups

Entropy

Mann Whitney U - test (independent)

0.00426476491403054

True

False

{‘Control’: 5.865591799223451, ‘Treat’: 5.86151065750034}

{‘Control’: 5.865591799223451, ‘Treat’: 5.86151065750034}

{‘Control’: 5.87099615514526, ‘Treat’: 5.557442303844718}

{‘Control’: [5.865591799223451, 5.987446600640773, 5.8670784396973925, 5.839555708376522, 5.969574526407146, 5.96134972606642, 5.874913870593128, 5.883527821378718, 5.883778304793762, 5.817900357834347, 5.865139545705292, 5.857118270596429], ‘Treat’: [5.86151065750034, 5.880446060580317, 6.016368189069645, 5.4153387381142695, 5.595997957362384, 5.455760308598386, 5.043437005348271, 4.8948447448447325, 5.012797646487333, 5.6236004755719025, 5.573743181915763, 5.541141425773674]}

Skewness

Mann Whitney U - test (independent)

0.000155795893087883

True

False

{‘Control’: -0.34478990613058524, ‘Treat’: 1.4509361530668134}

{‘Control’: -0.34478990613058524, ‘Treat’: 1.4509361530668134}

{‘Control’: -0.0691211178053974, ‘Treat’: 1.572599772068185}

{‘Control’: [-0.34478990613058524, -0.22967891006966357, 0.017633367378628025, -0.23330547043676542, -0.15587560298942282, 0.15549311955267353, -0.2144185871377651, 0.20025273895900966, 0.2494825439549606, -0.21159061388413317, 0.1401461999955842, 1.557492439982876], ‘Treat’: [1.4509361530668134, 1.2121412241636296, 0.5178865697186315, 1.4202875399156139, 1.214632959789608, 1.167055179393155, 2.8461464319879632, 2.8931051188421475, 2.996676248959314, 1.7175063605726535, 1.6942633910695566, 1.9061691013013036]}

AUC (total)

Mann Whitney U - test (independent)

0.000308044705627747

True

False

{‘Control’: 1977.0039242211726, ‘Treat’: 1150.8732976155613}

{‘Control’: 1977.0039242211726, ‘Treat’: 1150.8732976155613}

{‘Control’: 2037.19994608536, ‘Treat’: 446.8295477358479}

{‘Control’: [1977.0039242211726, 2488.317427756123, 1995.8340040624616, 1392.5936244420507, 2108.1807467814738, 1746.6977652366477, 2078.565888108258, 2185.576003863833, 2297.8221858652732, 1937.6167312010016, 2293.069739683835, 1058.6009747065525], ‘Treat’: [1150.8732976155613, 1050.9966217466347, 2148.5712962187454, 429.72898421706975, 593.2679571843505, 439.71657791710925, 175.26235323511924, 142.25950773242752, 162.63262352124667, 481.86142694920306, 453.9425175545865, 401.46239743060187]}

Mononucleosomal (100-200 bp)

Student’s t - test (independent) unequal variance)

0.000262647051538621

True

False

{‘Control’: 10.5, ‘Treat’: 15.5}

{‘Control’: 10.5, ‘Treat’: 15.5}

{‘Control’: 8.75, ‘Treat’: 29.05}

{‘Control’: [10.5, 10.9, 7.0, 13.8, 11.7, 13.3, 6.5, 5.0, 4.7, 5.3, 3.2, 14.9], ‘Treat’: [15.5, 20.1, 13.1, 31.7, 26.5, 27.8, 55.9, 58.4, 61.1, 29.3, 28.8, 32.4]}

Dinucleosomal (201-400 bp)

Student’s t - test (independent) assume equal variance)

3.30136607702543e-07

True

False

{‘Control’: 15.0, ‘Treat’: 25.1}

{‘Control’: 15.0, ‘Treat’: 25.1}

{‘Control’: 13.1, ‘Treat’: 28.4}

{‘Control’: [15.0, 11.6, 12.9, 17.7, 13.2, 13.0, 15.3, 10.3, 8.9, 16.5, 9.5, 23.7], ‘Treat’: [25.1, 25.6, 16.7, 28.2, 31.8, 30.7, 33.2, 19.8, 26.6, 28.6, 30.9, 30.3]}

Trinucleosomal (401-600 bp)

Mann Whitney U - test (independent)

0.225043021591528

False

False

{‘Control’: 12.8, ‘Treat’: 11.0}

{‘Control’: 12.8, ‘Treat’: 11.0}

{‘Control’: 11.85, ‘Treat’: 11.0}

{‘Control’: [12.8, 8.8, 12.6, 13.7, 9.6, 9.7, 14.8, 11.1, 10.0, 15.2, 10.8, 15.5], ‘Treat’: [11.0, 11.0, 8.5, 8.8, 12.0, 11.5, 1.6, 0.0, 0.0, 14.1, 15.1, 14.3]}

Tetranucleosomal (601-800 bp)

Mann Whitney U - test (independent)

0.000171495125256007

True

False

{‘Control’: 9.4, ‘Treat’: 0.0}

{‘Control’: 9.4, ‘Treat’: 0.0}

{‘Control’: 9.100000000000001, ‘Treat’: 5.2}

{‘Control’: [9.4, 6.6, 10.1, 9.6, 7.0, 7.1, 10.8, 9.3, 8.8, 11.1, 8.9, 7.6], ‘Treat’: [5.2, 5.6, 5.2, 3.7, 5.3, 5.0, 0.0, 0.0, 0.0, 7.1, 7.4, 6.9]}

Pentanucleosomal (801-1000 bp)

Mann Whitney U - test (independent)

3.587626116728915e-05

True

False

{‘Control’: 10.8, ‘Treat’: 0.0}

{‘Control’: 10.8, ‘Treat’: 0.0}

{‘Control’: 10.75, ‘Treat’: 4.800000000000001}

{‘Control’: [10.8, 8.0, 12.0, 10.6, 8.1, 8.5, 11.9, 11.5, 11.0, 12.1, 10.7, 6.7], ‘Treat’: [5.4, 5.8, 6.2, 0.6, 4.2, 3.6, 0.0, 0.0, 0.0, 6.2, 6.3, 5.7]}

Hexanucleosomal (1001-1200 bp)

Mann Whitney U - test (independent)

5.096629552848998e-05

True

False

{‘Control’: 7.4, ‘Treat’: 0.0}

{‘Control’: 7.4, ‘Treat’: 0.0}

{‘Control’: 7.45, ‘Treat’: 2.6}

{‘Control’: [7.4, 5.8, 8.2, 6.8, 5.7, 6.0, 7.5, 8.1, 7.9, 7.8, 7.6, 3.9], ‘Treat’: [3.8, 3.9, 4.5, 0.0, 2.1, 1.2, 0.0, 0.0, 0.0, 3.4, 3.3, 3.1]}

Heptanucleosomal (1201-1400 bp)

Mann Whitney U - test (independent)

7.07050733128538e-05

True

False

{‘Control’: 6.3, ‘Treat’: 0.0}

{‘Control’: 6.3, ‘Treat’: 0.0}

{‘Control’: 7.35, ‘Treat’: 2.1500000000000004}

{‘Control’: [7.5, 6.3, 8.2, 6.6, 6.1, 6.3, 7.2, 8.3, 8.4, 7.7, 8.2, 3.7], ‘Treat’: [4.4, 4.1, 5.0, 0.0, 1.6, 0.0, 0.0, 0.0, 0.0, 3.1, 2.9, 2.7]}

Octanucleosomal (1401-1600 bp)

Mann Whitney U - test (independent)

6.714883891516948e-05

True

False

{‘Control’: 6.1, ‘Treat’: 0.0}

{‘Control’: 6.1, ‘Treat’: 0.0}

{‘Control’: 6.4, ‘Treat’: 0.25}

{‘Control’: [6.7, 6.1, 7.3, 5.7, 5.9, 6.0, 6.1, 7.4, 7.7, 6.8, 7.9, 3.4], ‘Treat’: [4.3, 3.9, 5.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 2.5, 2.1, 0.5]}

Nonanucleosomal (1601-1800 bp)

Mann Whitney U - test (independent)

7.07118682460294e-05

True

False

{‘Control’: 4.8, ‘Treat’: 0.0}

{‘Control’: 4.8, ‘Treat’: 0.0}

{‘Control’: 4.8, ‘Treat’: 0.0}

{‘Control’: [4.8, 4.8, 5.2, 3.9, 4.7, 4.6, 4.4, 5.5, 5.9, 4.8, 6.3, 2.6], ‘Treat’: [3.5, 3.0, 4.1, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.2, 0.0, 0.0]}

Decanucleosomal (1801-2000 bp)

Mann Whitney U - test (independent)

7.995343962722956e-05

True

False

{‘Control’: 4.4, ‘Treat’: 0.0}

{‘Control’: 4.4, ‘Treat’: 0.0}

{‘Control’: 4.300000000000001, ‘Treat’: 0.0}

{‘Control’: [4.0, 4.5, 4.4, 3.2, 4.4, 4.2, 3.7, 4.8, 5.3, 3.9, 5.7, 2.4], ‘Treat’: [2.9, 2.7, 3.8, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]}

Polynucleosomal (2001-7000 bp)

Mann Whitney U - test (independent)

0.00166787381374531

True

False

{‘Control’: 9.5, ‘Treat’: 0.0}

{‘Control’: 9.5, ‘Treat’: 0.0}

{‘Control’: 16.95, ‘Treat’: 0.0}

{‘Control’: [9.5, 25.6, 11.4, 6.5, 22.7, 18.6, 11.2, 18.2, 21.3, 8.5, 21.1, 15.7], ‘Treat’: [18.0, 8.5, 25.5, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]}

Non-mono (> 250 bp)

Student’s t - test (independent) unequal variance)

5.565065976155082e-05

True

False

{‘Control’: 84.1, ‘Treat’: 57.1}

{‘Control’: 84.1, ‘Treat’: 57.1}

{‘Control’: 87.05000000000001, ‘Treat’: 49.2}

{‘Control’: [84.1, 84.9, 89.3, 79.3, 83.7, 81.4, 89.2, 92.8, 93.5, 89.9, 94.4, 75.3], ‘Treat’: [74.7, 65.8, 79.2, 28.8, 44.5, 39.9, 19.7, 11.3, 15.1, 57.1, 57.1, 53.9]}

Oligo (> 1250 bp)

Mann Whitney U - test (independent)

0.000558462027759282

True

False

{‘Control’: 30.9, ‘Treat’: 0.0}

{‘Control’: 30.9, ‘Treat’: 0.0}

{‘Control’: 36.5, ‘Treat’: 1.85}

{‘Control’: [30.9, 45.9, 34.7, 24.4, 42.6, 38.3, 30.9, 42.4, 46.7, 30.0, 47.4, 26.9], ‘Treat’: [32.2, 21.3, 42.3, 0.0, 1.1, 0.0, 0.0, 0.0, 0.0, 6.0, 4.3, 2.6]}

Mitochondrial/TF

Mann Whitney U - test (independent)

0.000122092699974362

True

False

{‘Control’: 0.5, ‘Treat’: 0.8}

{‘Control’: 0.5, ‘Treat’: 0.8}

{‘Control’: 0.5, ‘Treat’: 7.1}

{‘Control’: [1.4, 0.9, 0.5, 1.8, 0.6, 2.4, 0.5, 0.3, 0.2, 0.2, 0.0, 0.0], ‘Treat’: [0.8, 5.5, 2.2, 26.1, 15.8, 19.4, 8.7, 20.5, 11.4, 4.0, 2.8, 3.7]}

Short (100-400 bp)

Student’s t - test (independent) assume equal variance)

7.434964670831664e-07

True

False

{‘Control’: 25.5, ‘Treat’: 40.5}

{‘Control’: 25.5, ‘Treat’: 40.5}

{‘Control’: 22.15, ‘Treat’: 59.15}

{‘Control’: [25.5, 22.5, 19.9, 31.5, 24.8, 26.3, 21.8, 15.3, 13.5, 21.7, 12.7, 38.5], ‘Treat’: [40.5, 45.6, 29.8, 59.9, 58.3, 58.5, 89.1, 78.2, 87.7, 57.9, 59.8, 62.7]}

Long (> 401 bp)

Student’s t - test (independent) unequal variance)

8.979074392573866e-06

True

False

{‘Control’: 73.0, ‘Treat’: 0.0}

{‘Control’: 73.0, ‘Treat’: 0.0}

{‘Control’: 77.0, ‘Treat’: 29.200000000000003}

{‘Control’: [73.0, 76.4, 79.5, 66.6, 74.4, 71.0, 77.6, 84.3, 86.2, 78.0, 87.3, 61.5], ‘Treat’: [58.5, 48.5, 67.7, 13.0, 25.2, 21.3, 1.6, 0.0, 0.0, 37.6, 37.0, 33.2]}

Short (50-700 bp)

Student’s t - test (independent) assume equal variance)

4.3518925147105816e-07

True

False

{‘Control’: 44.2, ‘Treat’: 100.0}

{‘Control’: 44.2, ‘Treat’: 100.0}

{‘Control’: 40.2, ‘Treat’: 87.05}

{‘Control’: [44.2, 35.3, 37.8, 51.7, 38.6, 41.8, 42.3, 30.9, 27.6, 42.5, 27.7, 58.0], ‘Treat’: [55.2, 65.3, 43.2, 97.6, 89.5, 92.8, 100.0, 100.0, 100.0, 80.1, 81.8, 84.6]}

potential gDNA (1-5kB)

Mann Whitney U - test (independent)

0.000298833297689841

True

False

{‘Control’: 39.9, ‘Treat’: 0.0}

{‘Control’: 39.9, ‘Treat’: 0.0}

{‘Control’: 45.2, ‘Treat’: 5.0}

{‘Control’: [39.9, 52.9, 44.7, 32.7, 49.6, 45.7, 40.0, 52.3, 56.4, 39.6, 56.8, 31.5], ‘Treat’: [35.9, 25.9, 47.7, 0.0, 3.7, 1.2, 0.0, 0.0, 0.0, 10.2, 8.3, 6.3]}

likely gDNA (>3.5kB)

Mann Whitney U - test (independent)

0.123131990699528

False

False

{‘Control’: 0.0, ‘Treat’: 0.0}

{‘Control’: 0.0, ‘Treat’: 0.0}

{‘Control’: 2.1, ‘Treat’: 0.0}

{‘Control’: [0.0, 5.8, 0.0, 0.0, 4.4, 2.8, 0.2, 2.6, 3.1, 0.0, 1.6, 5.0], ‘Treat’: [10.0, 0.3, 7.1, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]}

very likely gDNA (>5kB)

Mann Whitney U - test (independent)

0.65122130965684

False

False

{‘Control’: 0.0, ‘Treat’: 0.0}

{‘Control’: 0.0, ‘Treat’: 0.0}

{‘Control’: 0.0, ‘Treat’: 0.0}

{‘Control’: [0.0, 0.1, 0.0, 0.0, 0.1, 0.0, 0.0, 0.1, 0.1, 0.0, 0.0, 0.1], ‘Treat’: [1.0, 0.1, 0.2, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]}

very very likely gDNA (>8kB)

Student’s t - test (independent) assume equal variance)

False

False

{‘Control’: 0.0, ‘Treat’: 0.0}

{‘Control’: 0.0, ‘Treat’: 0.0}

{‘Control’: 0.0, ‘Treat’: 0.0}

{‘Control’: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], ‘Treat’: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]}

short-to-long fragment ratio

Student’s t - test (independent) assume equal variance)

False

False

{‘Control’: 0.3493150684931507, ‘Treat’: inf}

{‘Control’: 0.3493150684931507, ‘Treat’: inf}

{‘Control’: 0.28771522642629677, ‘Treat’: 2.1010231401797665}

{‘Control’: [0.3493150684931507, 0.2945026178010471, 0.25031446540880503, 0.472972972972973, 0.3333333333333333, 0.3704225352112676, 0.28092783505154645, 0.1814946619217082, 0.15661252900232017, 0.2782051282051282, 0.14547537227949597, 0.6260162601626016], ‘Treat’: [0.6923076923076923, 0.9402061855670103, 0.4401772525849335, 4.607692307692307, 2.3134920634920633, 2.7464788732394365, 55.68749999999999, inf, inf, 1.5398936170212765, 1.6162162162162161, 1.8885542168674698]}

average_size

Mann Whitney U - test (independent)

0.00135394144309263

True

False

{‘Control’: 987.52, ‘Treat’: 1235.64}

{‘Control’: 987.52, ‘Treat’: 1235.64}

{‘Control’: 1131.74, ‘Treat’: 478.64}

{‘Control’: [987.52, 1382.23, 1102.22, 859.48, 1282.85, 1161.26, 1041.21, 1261.99, 1349.29, 999.0, 1342.87, 1008.7], ‘Treat’: [1235.64, 827.85, 1326.54, 378.28, 479.73, 347.68, 281.56, 224.09, 274.1, 530.14, 501.03, 477.55]}

modal_size

Mann Whitney U - test (independent)

0.0177025754599682

True

False

{‘Control’: 161.2, ‘Treat’: 155.1}

{‘Control’: 161.2, ‘Treat’: 155.1}

{‘Control’: 1063.75, ‘Treat’: 156.64999999999998}

{‘Control’: [1282.6, 161.2, 1163.0, 161.2, 167.3, 136.7, 986.2, 1184.8, 1380.4, 1141.3, 1434.8, 188.8], ‘Treat’: [5128.2, 158.2, 161.2, 133.7, 176.5, 149.0, 167.3, 142.9, 155.1, 155.1, 164.3, 155.1]}

median_size

Mann Whitney U - test (independent)

0.000243913267588222

True

False

{‘Control’: 841.4, ‘Treat’: 182.7}

{‘Control’: 841.4, ‘Treat’: 182.7}

{‘Control’: 917.2, ‘Treat’: 264.85}

{‘Control’: [827.6, 1108.7, 931.0, 669.0, 993.1, 903.4, 841.4, 1065.2, 1163.0, 841.4, 1184.8, 533.3], ‘Treat’: [568.9, 396.5, 937.9, 182.7, 237.8, 213.3, 182.7, 149.0, 167.3, 316.3, 316.3, 291.9]}

peak_0

Mann Whitney U - test (independent)

0.124620803996843

False

False

{‘Control’: 161.22, ‘Treat’: 155.1}

{‘Control’: 161.22, ‘Treat’: 155.1}

{‘Control’: 162.755, ‘Treat’: 156.63}

{‘Control’: [152.04, 161.22, 164.29, 161.22, 167.35, 136.73, 986.21, 161.22, 158.16, 1141.3, 1434.78, 188.78], ‘Treat’: [185.71, 158.16, 161.22, 133.67, 176.53, 148.98, 167.35, 142.86, 155.1, 155.1, 164.29, 155.1]}

peak_1

Mann Whitney U - test (independent)

0.2

False

False

{‘Control’: 1282.61, ‘Treat’: 1542.25}

{‘Control’: 1282.61, ‘Treat’: 1542.25}

{‘Control’: 1086.96, ‘Treat’: 1542.25}

{‘Control’: [1282.61, 361.63, 1163.04, 1086.96, 375.58, 330.23, 1184.78, 1380.43, 400.0], ‘Treat’: [1542.25]}

max_peak

Mann Whitney U - test (independent)

0.00458877414557382

True

False

{‘Control’: 161.22, ‘Treat’: 155.1}

{‘Control’: 161.22, ‘Treat’: 155.1}

{‘Control’: 1063.755, ‘Treat’: 156.63}

{‘Control’: [1282.61, 161.22, 1163.04, 161.22, 167.35, 136.73, 986.21, 1184.78, 1380.43, 1141.3, 1434.78, 188.78], ‘Treat’: [185.71, 158.16, 161.22, 133.67, 176.53, 148.98, 167.35, 142.86, 155.1, 155.1, 164.29, 155.1]}

peak_2

None (peak unique to group)

1

True

{‘Control’: 1542.25}

{‘Control’: 1542.25}

{‘Control’: 1456.52}

{‘Control’: [1542.25, 1456.52, 1369.57]}

Result: In this example, the average_size, max_peak, and also the first peak size do show a statistical difference between the two groups, as the Kruskal Wallis test computed a p value < 0.05. Unique peaks refer to peaks that only occur in one group, but not in the other. Because they are unique to a group, no statistical comparison is performed for those peaks.

Paired analyses

In case your samples are related (e.g. different time points of the same individual are to be compared), you will need to tell DNAvi to run the appropriate statistical test by adding the command line option - - paired.

DNAvi will then either perform a - Student’s t - test (paired) - if normal distribution is assumed - Wilcoxon signed-rank test (paired) - if the hypothesis of a normal distribution is rejected