[{'role': 'system', 'content': "You are an expert in machine learning and your task is to classify code snippets into one of the following categories: ['helper_functions', 'load_data', 'data_exploration', 'data_preprocessing', 'evaluation', 'modelling', 'prediction', 'result_visualization', 'save_results', 'comment_only']."}, {'role': 'user', 'content': 'Identify the single most appropriate category to which the provided code belongs. Provide your response as a single category label without any additional information, commentary, or personal opinions.\\nPython Code:worst_sd_of_population = 0.5\nwidth_in_sds = 4 # For 95% of a normal distribution, mean +/- 2 SDs\ndesired_width = 0.03\nsample_size = (worst_sd_of_population * width_in_sds / desired_width) ** 2\nsample_size'}, {'role': 'assistant', 'content': 'modelling'}]