Lexical density refers to the number of lexical (meaning carrying) words in a text out of the entire number of words in that text, expressed as a percentage. Lexical words include all nouns, verbs, adjectives and adverbs and may include language chunks and phrases, etc. In computational linguistics, lexical density can even be a comparison of the number of full clauses in a text out of the entire number of words. The calculation is based on the purpose of the data.
For our purposes here at UWCSEA East, we have devised a calculation of our own, based on computational linguistics, but easier and more accessible to us. It is called Nominal Density and refers to the number of nouns in a text over the entire number of words, expressed as a percentage. The reason we have chosen this look at lexical density is that it indicates the register or level of academic language through the use of nouns. Academic language often requires the use of the passive and of nominalization (verb or adverbial forms expressed as nouns) to increase the register or formality of a text.
If a student needs a strategy to increase register in a text, this is something you might suggest. Please see the examples below:
Here are some examples of more nominalized sentences.
2. The temperature of the planet is rising as a result of global warming.
→ The rise of the planet’s temperature is a result of global warming.
3. The business report indicates that sales figures are down 10% on last month, which is worrying.
→ The indication of the business report that sales figures are down 10% on last month is worrying.
4. A team of scientists analysed the data in the lab before they wrote their report.
→ The analysis of data by a team of scientists in the lab was undertaken before writing a report.
5. Mathematics and physics experts have produced a mathematical formula which explains the modern phenomena of network science.
→ The production of a mathematical formula by mathematics and physics experts has explained the modern phenomena of network science.
Here are some examples of texts that are nominally fairly high. The nominal density is listed below each text.
Text A BACTERIAL GROWTH
When scientists grow bacteria in a lab, they can observe four distinct stages of growth over time, as shown in the graph (not pictured here). First, the bacteria get used to their new environment during a period of time called the lag phase. Next, in the growth phase, the cells begin to reproduce and the population grows rapidly. As the population grows, the bacteria begin to use up the food in their environment, and some cells start to die. The bacteria soon reach the stationary phase, when cells are dying as fast as they are reproducing. Finally the bacteria use up all the available food and reach the decline phase, when many cells die and only a few new cells are formed.
Temperature affects the growth rates of bacteria, either speeding up reproduction or slowing it down, Under ideal conditions, bacteria will reach their maximum growth rate. The diagram (not pictured here) shows, however, that some bacteria, called psychropiles, thrive at cold temperatures (-10 to 25C) while mesophiles grow best at moderate temperatures (20 to 50C) and thermophiles prefer extreme heat (45 to 80C). When the temperature is either above or below the optimal range for a certain type of bacteria, its reproduction rate is slower.
One strain of E.coli, a mesophile which causes food poisoning, can sometimes be found on foods like meats and vegetables. Understanding how temperature affects bacterial growth helps people know how to handle food and prevent the spread of foodborne illnesses.
When scientists grow bacteria in a lab, they can control and manipulate variables such as the temperature, the acidity and the concentration of oxygen and salt of the medium in which the bacteria are growing. They can then observe how changes in each variable affect the bacteria population. In the real world, however, the complexity of the environment makes it difficult to explain changes in the growth of bacteria. For example, some varieties of bacteria inhabit soil, which is subject to seasonal variation and other environmental disturbances that alter its properties. These variables interact to speed and slow the growth of bacteria in unpredictable ways. There are periods of time when the bacteria in soil thrive, as well as periods when the population decreases. Even when scientists have made these observations in the outdoors, they may be uncertain about which environmental factor is causing the population to grow or decline.
Source: Wida Model Student Reading Test Booklet (2011) Board of Regents of the University of Wisconsin
Nominal Density 28.2%
Nouns: 112
Words: 397
112/397 x 100 = 28.2
Text B ANCIENT CIVILIZATIONS
Traveling south from the desert of northern Mexico, the Aztecs first arrived in central Mexico in the mid-14th century. They settled there and built a grand capital city called Tenochitilan, which was central to Aztec life and culture. Large public buildings, temples and schools were built in the center of the city. They developed advanced farming methods to farm the swampy land that surrounded the city, and they founded an economy based on the corn, tomatoes and chocolate that they produced. The Aztecs never developed a true system of writing, but they did produce books of maps and pictures that recorded their history, geography and religious rituals. Although they were known as warriors, the Aztecs were defeated by the Spanish in 1519, less than 200 years after they created their empire.
Another ancient central American people, the Maya, were predecessors of the Aztecs. Maya civilization reached its peak from about 600 to 900 CE, when urban centres such as the city of Tikal became the heart of cultural and intellectual development. During this time, the Maya made many advances in areas such as mathematics, art, astronomy, and architecture. They developed a reliable way to track the stars and planets, constructed cities with complex structures, invented the concept of zero, and created a sophisticated system of writing. Archeologists have learned a great deal about their civilization based on the written records that they left behind.
Surprisingly, no written records of the Maya have been discovered that date beyond approximately 900 CE. Theories about the collapse abound. One theory in particular claims that the Mayas’ intensive farming methods, which involved clear-cutting forests to create farmland, led to deforestation that made them vulnerable to the effects of drought. In support of this theory, researchers have found evidence that Maya buildings used less wood in their construction as the population increased. Additionally, atmospheric scientists have shown that once trees are cut down, sunlight causes water to evaporate from the land, increasing the severity of any water shortages. Both Mayan agriculture and city planning were developed during a period of relatively high precipitation that lasted several decades, so Maya farms and cities were designed to use large amounts of water. When the climate became much drier, around 750CE, the effects were devastating.
Source: Wida Model Student Reading Test Booklet (2011) Board of Regents of the University of Wisconsin
Nominal Density: 30.02%
Nouns: 114
Words: 377
114/377 x 100 = 30.02
Text C: Why We Desperately Need Better Cybersecurity
by Diane Keller
The Internet of Things is an idea of potentially unending consequence and infinite possibility.
Essentially, it is the drive to make every device in our everyday lives communicate with other devices over the internet. It would mean that your entire house can be controlled with your phone and, one day hopefully, your entire life. Everything from your car to your refrigerator will be able to communicate, not only with your phone but other devices and servers all over the world.
Its potential, as you might assume, is positively staggering as an entirely interconnected world would mean unprecedented access to data that can be used to shape the future. It is a goal towards uniform access to the internet and the ability to communicate with other people worldwide.
To create a world above the physical, to make an internet without borders. It is the dream of many entrepreneurs and writers as we see the day of complete coverage draw near.
In this time, however, we must consider every eventuality and potentiality if such actualization were to occur.
This is a truly ailing problem as the threat of hacking becomes much greater given the sheer number of access points that are being created to facilitate the Internet of Things.
By the sheer principle of technological evolution, the number of access points that are being created is going to be a real problem for international users and a real joy to hackers everywhere. As major tech companies push for greater access, devices must be made and acquired for potential internet users to access the web.
There is no shortage there, however, as the number of smartphones, and companies making them, seem to increase almost daily. It is no small feat to manufacture a nation’s weight in phones, but our major mobile companies are doing it with ease.
The problem lies in the fact that every smartphone is a potential access point for any malicious actor to exploit. The law of averages alone dictates as the overall number of devices increases so will the number of hackers. This isn’t including all of the laptops and tablets that are already out there being used with malicious intent.
Source: https://www.computer.org/web/computingnow/security/content?g=53319&type=article&urlTitle=why-we-desperately-need-better-cybersecurity
Nominal Density: 24.2%
Nouns: 88
Words: 363
88/363 x 100 = 24.2%
Text D: Hong Kong Observatory tracks hurricane-force winds as Super Typhoon Mangkhut set to arrive Sunday
Kris Cheng
The Hong Kong Observatory has upgraded the highest estimated wind speed of Super Typhoon Mangkhut to the highest level on the Beaufort Scale – meaning it currently has hurricane force winds.
The government held a rare cross-department press conference on Friday afternoon over the super typhoon.
The Observatory initially estimated that the highest offshore wind speed could be at level 11, but upgraded it to level 12 on Friday, meaning that the speed could exceed 118 kilometres per hour.
“It is quite likely for storm signal no. 8 to be issued [on Sunday],” said Cheng Cho-ming, assistant director of the Observatory. “As for whether there will be a higher warning signal… it depends on the strength and path of Mangkhut after it passes Luzon.”
Cheng added that it was difficult to estimate how long the T8 signal will last. Public services are suspended as long as the signal is hoisted.
Mangkhut is expected to be closest to Hong Kong on Sunday at daytime. Its strength will decrease when it is further away from Hong Kong on Monday, but it will depend on the rate at which it slows.
“Regardless, the wind will be very strong. The public should take preventive measures as soon as possible,” Cheng said.
The strength of Mangkhut may change when it moves across Luzon into South China Sea, but it will maintain the strength of a super typhoon after entering the South China Sea.
The Observatory said Mangkhut is expected to skirt south of Hong Kong. It urged members of the public to stay away from the shoreline and not to engage in water sports.
At special press conference on Friday, Secretary for Security John Lee said that more personnel and equipment will be on standby for Mangkhut compared to last year’s Signal No.10 storm Hato.
“Each department must have crisis awareness, conduct a full assessment, and prepare and plan for the worst,” Lee said.
Deputy Director of Home Affairs Vega Wong said that evacuation efforts were already underway for low-lying and flood-prone areas such as Tai O, Lei Yue Mun and some outlying islands.
Source: https://www.hongkongfp.com/2018/09/14/observatory-says-t8-likely-sunday-mangkhut-upgraded-highest-level-beaufort-scale/
Nominal Density: 18.2%
Nouns: 64
Words: 350
64/350 x 100 = 18.2%