You are applying gender classification and want to estimate the portion of correctly classified observation.

To estimate the portion of correctly classified observations in gender classification, you would follow these steps:

1. Collect Data: Gather a dataset that includes the gender of individuals and the features you are using for classification. This could be anything from physical characteristics to purchasing habits.

2. Preprocess Data: Clean and preprocess your data. This might involve handling missing values, normalizing numerical data, or encoding categorical data.

3. Train a Model: Use a machine learning algorithm to train a gender classification model on your data. This could be a simple algorithm like logistic regression, or a more complex one like a neural network.

4. Test the Model: Split your data into a training set and a test set. Train your model on the training set, then use it to predict the genders of the observations in the test set.

5. Calculate Accuracy: Compare the model's predictions to the actual genders of the observations in the test set. The portion of correctly classified observations is the number of correct predictions divided by the total number of predictions. This is known as the accuracy of the model.

6. Evaluate the Model: Besides accuracy, you might also want to consider other metrics like precision, recall, and F1 score, especially if your dataset is imbalanced. You might also want to use cross-validation to get a more robust estimate of your model's performance.

7. Iterate: If the accuracy is not satisfactory, you might need to go back to previous steps. You could try using different features, a different model, or different hyperparameters for your model. You might also need to collect more data.