Lensa ML
Lensa ML

Learning Curves

Step 1 of 6

What is a Learning Curve?

Accuracy vs. training size

0%20%40%60%80%100%1058105153200Training SizeAccuracyTrainValidationN=80
N
80
TRAIN ACC
99.0%
VAL ACC
70.0%
GAP
29.0%

A learning curve shows how model performance changes as you add more training data. The gap between training and validation accuracy reveals whether your model is underfitting or overfitting.

Step 1 of 6: What is a Learning Curve?

Accuracy vs. training size

0%20%40%60%80%100%1058105153200Training SizeAccuracyTrainValidationN=80
N
80
TRAIN ACC
99.0%
VAL ACC
70.0%
GAP
29.0%

A learning curve shows how model performance changes as you add more training data. The gap between training and validation accuracy reveals whether your model is underfitting or overfitting.

Step 2 of 6: High Bias Pattern

Both curves plateau low

Data follows a curve — degree-1 polynomial can't capture it
x (feature)y (target)true patterndegree-1 fit
0%20%40%60%80%100%1058105153200Training SizeAccuracyTrainValidationplateau
DEGREE
1
FIT ERROR
0.025
TRAIN ACC
92.7%
PLATEAU
92.7%

A straight line can't capture this curved pattern — it misses the shape entirely. Both learning curves plateau low because the model is fundamentally too simple.

Step 3 of 6: High Variance Pattern

A persistent gap

Degree-4 polynomial fits 5 training points — memorizes train, fails on validation
x (feature)y (target)Train (5)Val (10)overfit model
0%20%40%60%80%100%1058105153200Training SizeAccuracyTrainValidation42% gap
TRAIN ERR
0.0000
VAL ERR
141.524
ERR RATIO
1415235x
GAP
42.2%

The model memorizes training data (low train error) but the wiggly curve misses validation points. More training data would help tame the overfitting.

Step 4 of 6: Adding More Data

Does it help?

0%20%40%60%80%100%10133255378500Training SizeAccuracyTrainValidationN=80
N
80
GAP
28.4%
TREND
flat
DIAGNOSIS
High Bias

With a simple model, the gap is flat — both curves plateau low. More data won't help. You need a more complex model to improve.

Step 5 of 6: Changing Model Complexity

The other lever

0%20%40%60%80%100%1058105153200Training SizeAccuracyTrainValidationN=100Good Fit
COMPLEXITY
5
TRAIN ACC
99.0%
VAL ACC
70.0%
GAP
29.0%

Good fit! The model balances complexity and generalization — train and validation accuracies are both high with a small gap.

Step 6 of 6: Diagnose Your Model

Interactive scenario explorer

0%20%40%60%80%100%1058105153200Training SizeAccuracyTrainValidationOVERFIT
DIAGNOSIS
OVERFIT
ACTION
Simplify or add data
TRAIN ACC
99.0%
VAL ACC
70.0%

Your model is overfitting — there's a large gap between train and validation. Simplify the model (regularization, fewer parameters) or collect more training data.