def convert_to_table(header, rows):
    """
    Create an HTML table out of the sample data.

    Args:
        header (str): The table header
        rows (List[str]): A list of rows as strings

    Returns:
        A dataset sample in the form of an HTML <table>
    """
    header_html = '<tr><th>{}</th></tr>'.format('</th><th>'.join(header))
    rows_html = ['<tr><td>{}</td></tr>'.format('</td><td>'.join(row)) for row in rows]

    if rows:
        table = '<table>{header}\n{rows}</table>'.format(
            header=header_html, rows='\n'.join(rows_html))
    else:
        table = None

    return table