SCIN 137 AMU week 5 lesson lab Weather Analysis Lab Introduction to Meteorology American Military university
Introduction
Topics to be covered include:
- Introduction to data measurement
- Categories of measurement
- Principles of accuracy versus precision
- Examples of common lab equipment for data measurement
- Role of significant digits in data analysis
In the last lesson, we introduced the basics of experimental design and emphasized the importance of randomization, sample size, and controlling outside variables to avoid bias and ensure the validity of the results. Now we will turn our attention to the product of such careful design, which is data collection and measurement. We will learn the basics of data measurement, such as the difference between quantitative and qualitative data, accuracy versus precision, and examples of common lab equipment used for data collection. We will set the foundation for learning about data management by discussing the importance of significant digits and practice basic unit conversions.
Why does the United States Still use the English System?
Living in the United States, you probably take for granted that we measure distances in feet and miles and weight in pounds, which utilizes the English or Imperial system. However, if you were to travel overseas, you would quickly find that most of the rest of the world uses the metric system. The speedometers on automobiles would measure speed in kilometers instead of miles, meaning you would have to take extra care when driving to avoid a speeding ticket. Scales would be deceiving by measuring your weight in kilograms instead of pounds, and thermometers would read temperatures in degrees Celsius instead of Fahrenheit.
The English system of measurement has caused controversy in terms of the United States’ industry, politics, and scientific measurements. In 1999, the Mars Climate Orbiter, which cost NASA $123 million, was destroyed when it veered off course and burned up in Mars’ atmosphere. NASA later revealed that part of the orbiter’s navigation system used English units, while the other part used metric units (Isbell, Hardin, & Underwood, 1999). Later, in 2015, Rhode Island senator Lincoln Chafee made a short bid for the presidency in the 2016 election and declared, “Let’s join the rest of the world and go metric” (Appelbaum, 2015). Many voters scorned the idea, and critics labeled it the worst idea of his campaign.
A universal metric system provides a common language for nations, individuals, and corporations around the world to communicate, trade, and share information (Appelbaum, 2015). Most of the world began moving to the metric system in the late nineteenth century, but United States manufacturers of high-end machine tools strongly opposed the metric system in the 1870s. They had based their entire system for manufacturing machines and even cutting screw threads on the English system. Citing the expense of redesigning their machines, these manufacturers successfully blocked the adoption of the metric system in Congress throughout the late nineteenth and twentieth century (Appelbaum, 2015).
For now, the United States has settled into a compromise regarding English and metric units. Rulers and tape measures typically have inches on one side and meters on the other, and schools teach students to convert between the two systems of measurement. Scientific manuscripts also must take the two measurement systems into account. Researchers must keep their measurements consistent and be prepared to convert between systems as necessary. Furthermore, researchers who use English measurements must comprehend the metric system to fully understand the results of international papers. We will compare and contrast English and metric units in more detail later in the lesson and practice sample unit conversions.
What is Data Measurement?
Data measurement and collection occurs once researchers have designed their experiment, carefully documented their procedures, and begin actively conducting their procedures. Data measurement involves collecting numerical information, such as taking an object’s mass or weight, using a thermometer to read temperature, or using a ruler to measure an object’s height. As a result, researchers must keep careful record of units of measurement, which we will discuss later in the lesson.
Data can be defined as any facts or information collected for statistical analyses. Researchers design their experiments with data measurement in mind. In many cases, a researcher may know exactly what type of data he or she wishes to collect to test a hypothesis and designs a study that will provide those exact measurements. Experimental procedures that are carefully documented and followed with ensure that the intended data to test the experimental hypothesis is collected. Such finely tuned experimental design also requires a thorough knowledge of data management and the types of statistical analyses that are most appropriate to analyze the data.
Quantitative vs. Qualitative Measurement
Data typically falls under one of two categories in any field of science. Quantitative data, also known as empirical research, consists of pieces of information that we can accurately and precisely measure and express as numbers (University of Wisconsin-Madison, 2016). Examples include measurements of height, temperature, length, width, and mass. As we’ve already discussed, the scientific method relies heavily on quantitative data, as this is the only data that researchers can use for rigorous statistical analyses.Qualitative data , on the other hand, provides information about qualities that we cannot measure but can observe such as colors, textures, appearances (University of Wisconsin-Madison, 2016). Examples include statements about the softness of a surface or the color of flower.
So, if we cannot measure qualitative data with numbers, does that mean it is useless? Not necessarily, as our next case study illustrates.
Case Study: Does Qualitative Data Have Value in Science?
Up until this point, we have focused almost exclusively on the value of quantitative data in science. However, qualitative data can also provide valuable information for research in certain situations. For example, a study might seek to test bird behavioral response in response to different flower colors. Both the behavioral response (dependent variable) and flower color (independent variable) are qualitative measures. In the previous example of testing antibiotic efficacy, the treatment categories are qualitative and the dependent variable (got better or did not) is also qualitative.
Overall, there is no single best way to conduct a study, as the methods can vary drastically depending on the field of research. Mathematical sciences, chemistry, physics, and biology may rely almost exclusively on quantitative data there are also examples of valuable qualitative data in areas biology like ecology and behavior. Experienced researchers often use both forms of data to provide the most useful results for their studies.
The Four Levels of Data Measurement
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- Levels of MeasurementWhen we’re working with qualitative or quantitative data, we can classify information into varying levels of measurement. These four measurement scales offer ways to categorize different types of variables, and each scale progressively builds off the previous one in terms of complexity. While you may not hear these terms used outside of school, they are considered standard language within academia and statistics. Let’s examine each of these four measurement scales in term, starting with the simplest.
Tools of the Trade: Basic Laboratory Equipment
Now that we’ve learned foundational principles of data measurement, we’re going to introduce some of the most common pieces of laboratory equipment used to collect data. You will most likely encounter many of these instruments if you take future science courses with an in-class laboratory component or work in a medical or industrial lab. Laboratories provide a well-controlled environment, which facilitate accurate and precise measurements. For example, laboratory environment can control variables that could affect results like temperature, humidity, light, etc. There is a range of equipment available to any lab from inexpensive equipment to high-tech, expensive equipment. Often the cost is related to the ability to take measurements with greater precision and accuracy in measurements. Common variables that are measured include height, weight, length, volume, and temperature. Equipment can be fragile and easily broken, so researchers must often confine them to controlled laboratory settings. Other equipment is manufactured with stressful field conditions in mind since widely fluctuating temperatures and humidity and exposure to hard and rough surfaces.
Glassware
Erlenmeyer flasks and petri dishes
Laboratory experiments often require a wide range of glassware for mixing, storing, and measuring solutions. Glass can stand up to heat from Bunsen burners, is easy to clean, and minimizes the risk of bacterial growth that could contaminate other procedures. Erlenmeyer flasks are conical shaped to allow for titration (when a known concentration of a chemical is used to determine the concentration of an unknown solution) and mixing of liquids while minimizing air contamination (Chemiasoft, 2014). You can gently swirl a solution in an Erlenmeyer flask without worrying about the liquid splashing out onto your hands. Standard beakers come in many different sizes for measuring volumes of liquid, but they, along with Erlenmeyer flasks, measure with relatively low accuracy. Graduated cylinders and volumetric flasks measure liquids with much greater accuracy, and pipettes are small syringe-shaped cylinders that can transfer more exact amounts of liquid between solutions (Chemiasoft, 2014).
Microscopes
Since the invention of the first microscope in 1590 (Cox, 2013), these instruments have been a standard piece of laboratory equipment for cellular, genetic, and micro-organismal research. You are probably the most familiar with light microscopes, which pass a beam of light through a specimen.
Simple microscopes, also known as dissecting microscopes, use a single lens that moves up and down over an object placed on a stationary platform (Medhekar, 2016).
Compound microscopes use two sets of lenses, known as the objective and ocular lenses, to magnify a specimen (Medhekar, 2016). Compound microscopes are also commonly used in biology laboratories to view preserved slides and wet mounts that students make using clean slides and coverslips. Finally, electron microscopes, invented in 1932, pass beams of electrons through a specimen for even greater magnification and resolution.
Transmission electron microscopes view the internal structures of cells, while scanning electron microscopesare used to study the surfaces of cells and microscopic organisms (Medhekar, 2016). The choice of microscope depends on the type of experiment and level of detail (magnification) needed. Technology is often key to the scientific process as it allows us to detect and measure data that we otherwise with our own senses alone could not. Advances in technology can also result in advances in scientific knowledge.‹1/5 ›
- Simple Microscope
Rulers
Rulers and tape measures are simple, yet indispensable tools for measuring lengths, heights, and widths of specimens. As we learned at the beginning of the lesson, the United States strikes a compromise between the English and metric systems of measurement by using inches on one side and centimeters on the other.
Scales and Balances
People unfamiliar with laboratory equipment often use the terms “scale” and “balance” interchangeably, but each one provides a different measurement. Scales measure an object’s weight as a function of gravity, which means that an object’s weight changes as the force of gravity changes (Kennedy, 2017). A balance, on the other hand, uses a lever with plates and standard masses to determine an object’s mass. An object’s mass does not change even if gravity changes and is defined as the amount of matter in the object (Kennedy, 2017).
Thermometers
Laboratory thermometers also come in several varieties for measuring changes in temperature with a high degree of accuracy and precision. You are probably most familiar with liquid-in-glass thermometers, which either contain mercury or red alcohol that expands and rises in the tube as temperature increases (Engineering360, 2017). Mercury has become less common, and any thermometers containing mercury require special disposal methods to avoid risking human health or polluting the environment. Infrared thermometers are easy-to-use, non-contact devices that convert infrared energy into an electrical signal to determine the temperature (Engineering360, 2017).
Thermometers usually display temperature in degrees Celsius or Fahrenheit, but chemistry also uses the Kelvin scale for recording temperature. Each unit on this scale is called a Kelvin rather than a degree but is equal to a degree on the Celsius scale. Furthermore, the Kelvin scale defines “absolute zero” as the temperature at which molecules would stop moving (Zimmermann, 2013). While researchers have not achieved absolute zero in a laboratory setting, the Kelvin scale uses it as its starting point for measuring temperature. The Kelvin scale has no negative numbers but starts at zero Kelvins, or absolute zero, and allows for simple unit conversions to the Celsius scale (Zimmermann, 2013).