Sample Types and Errors in Research

Sample Types and Errors in Research Basics Print Sample Types and Errors in Research By Kendra Cherry facebook twitter Kendra Cherry, MS, is an author, educational consultant, and speaker focused on helping students learn about psychology. Learn about our editorial policy Kendra Cherry Updated on February 14, 2020 More in Psychology Basics Psychotherapy Student Resources History and Biographies Theories Phobias Emotions Sleep and Dreaming In statistics, a sample is a subset of a population that is used to represent the entire group as a whole. When doing research, it is often impractical to survey every member of a particular population because the sheer number of people is simply too large. To make inferences about the characteristics of a population, researchers can use a random sample. Why Do Researchers Use Samples? When researching an aspect of the human mind or ?behavior, researchers simply cannot collect data from every single individual in most cases. Instead, they choose a smaller sample of individuals that represent the larger group.?? If the sample is truly representative of the population in question, researchers can then take their results and generalize them to the larger group. Types of Sampling In psychological research and other types of social research, experimenters typically rely on a few different sampling methods. 1. Probability Sampling Probability sampling means that every individual in a population stands an equal chance of being selected. Because probability sampling involves random selection, it assures that a different subset of the population has an equal chance of being represented in the sample. This makes probability samples more representative, and researchers are better able to generalize their results to the group as a whole. There are a few different types of probability sampling: Simple random sampling is, as the name suggests, the simplest type of probability sampling. Researchers take every individual in a population and randomly select their sample, often using some type of computer program or random number generator.Stratified random sampling involves separating the population into subgroups and then taking a simple random sample from each of these subgroups. For example, research might divide the population up into subgroups based on race, gender, or age and then take a simple random sample of each of these groups. Stratified random sampling often provides greater statistical accuracy than simple random sampling and helps ensure that certain groups are accurately represented in the sample.Cluster sampling involves dividing a population into smaller clusters, often based upon geographic location or boundaries. A random sample of these clusters is then selected and all of the subjects within in cluster are measured. For example, imagine that you are trying to do a study on school principals in your state. Collecting data from every single school principal would be cost-prohibitive and time-consuming. Using a cluster sampling method, you randomly select five counties from your state and then collect data from every subject in each of those five counties. 2. Nonprobability Sampling Non-probability sampling, on the other hand,  involves selecting participants using methods that do not give every individual in a population an equal chance of being chosen. One problem with this type of sample is that volunteers might be different on certain variables than non-volunteers, which might make it difficult to generalize the results to the entire population.?? There are also a couple of different types of nonprobability sampling: Convenience sampling involves using participants in a study because they are convenient and available. If you have ever volunteered for a psychology study conducted through your universitys psychology department, then you have participated in a study that relied on a convenience sample. Studies that rely on asking for volunteers or by using clinical samples that are available to the researcher are also examples of convenience samples.Purposive sampling involves seeking out individuals that meet certain criteria. For example, marketers might be interested in learning how their products are perceived by women between the ages of 18 and 35. They might hire a market research firm to conduct telephone interviews that intentionally seek out and interview women that meet their age criteria.Quota sampling involves intentionally sampling a specific proportion of a subgroup within a population. For example, political pollsters might be interested in researching the opinions of a population on a certain political issue. If they use simple random sampling, they might miss certain subsets of the population by chance. Instead, they establish criteria that a certain percentage of the sample must include these subgroups. While the resulting sample may not actually be representative of the actual proportions that exist in the population, having a quota ensures that these smaller subgroups are represented. Learn more about some of the ways that probability and nonprobability samples differ. Sampling Errors Because sampling naturally cannot include every single individual in a population, errors can occur.?? Differences between what is present in a population and what is present in a sample are known as sampling errors. While it is impossible to know exactly how great the difference between the population and sample may be, researchers are able to statistically estimate the size of the sampling errors. In political polls, for example, you might often hear of the margin of errors expressed by certain confidence levels. In general, the larger the sample size the smaller the level of error. This is simply because as the sample becomes closer to reaching the size of the total population, the more likely it is to accurately capture all of the characteristics of the population. The only way to completely eliminate sampling error is to collect data from the entire population, which is often simply too cost-prohibitive and time-consuming. Sampling errors can be minimized, however, by using randomized probability testing and a large sample size.

What Makes a Dry Ice Bomb Dangerous

Dry ice in a sealed container has the potential to become a dry ice bomb. Heres a look at the dangers associated with a dry ice bomb and how to avoid them. What Is a Dry Ice Bomb? A dry ice bomb simply consists of dry ice that is sealed in a rigid container. The dry ice sublimates to form carbon dioxide, which exerts pressure on the wall of the container until... BOOM! Although it is legal to make a dry ice bomb in some places, providing it is used for educational or entertainment purposes and not destruction, these devices are dangerous to make and use. Plus, many of the people who make a dry ice bomb do so accidentally, not realizing how quickly dry ice produces pressure or how much pressure it exerts as it turns into gas. Dry Ice Bomb Dangers A dry ice bomb causes an explosion with the following undesirable effects: Extremely loud noise. You can permanently damage your hearing. This is the reason dry ice bombs are illegal in Tennessee, for example.The explosion throws pieces of the container which act as shrapnel. It also throws pieces of dry ice, which could get embedded in your skin, producing frostbite and extreme tissue damage as the carbon dioxide freezes tissue and sublimates to form gas bubbles.You cant gauge how pressurized the container is so you cant defuse the bomb. If you have a dry ice bomb that doesnt go off, its still dangerous. You cant approach it to try to release the pressure, since this would put you at risk. The only good way to eliminate the hazard is to rupture the container from a distance. This often involves having a law enforcement officer shoot the container, which is a situation to avoid. Accidental Dry Ice Bombs While you may not set out to make a dry ice bomb, if youre working with dry ice you need to avoid making one unintentionally. Dont seal dry ice in a latching cooler.Dont close it up in a sealed fridge or freezer.Dont close it in a plastic bottle.Dont seal dry ice in anything! This is an extremely risky project. However, its important to know why its risky and how to avoid endangering yourself working with this useful and interesting material.

Stonewall Jackson Embodying The American Dream 10261999

Stonewall Jackson: Embodying the American Dream 10261999 1 Thomas â€Å"Stonewall† Jackson once said, â€Å"You may be whatever you resolve to be,† (Biography.com Editors). Many of the greatest men throughout history, including Stonewall Jackson, came from small beginnings, yet with perseverance, achieved their wildest dreams. Furthermore, many of these men were inspirational figures to others during his or her time; alike how Stonewall Jackson was idolized by many southerners due to being born with a family facing an uphill battle against death and poverty, but overpowered all odds and became a triumphant military general. However, Jackson was not only a successful general but also taught a variety of sciences and artillery tactics at VMI and†¦show more content†¦Also, he did not allow others to prevent him from becoming an influential man of his time. For instance, Jackson was poorly educated due to his deprived upbringing, so when he attended the military institute, West Point that was based in New York, he was port rayed as a lesser man than the other cadets and was often heckled by other students since he was much older and his lack of schooling, but with determination, he graduated 17th in his class (Biography.com Editors). Without a doubt, Jackson would not have been such a compassionate, powerful man without having to battle his own adversities, so, if Jackson was born into a privileged family, he most likely would not have such endurance for problems that he would face on the battlefield nor benevolence for the common man, which created the bond between him and his men. Additionally, it would be unlikely for him to be as successful in the military without the personality he developed throughout his youth since he would not compose the relationship with his men due to lack of similarities and he would almost certainly not be as determined to become the greatest he can be for his men. Nonetheless, the challenges he faced at an early age caused him to only become tougher and provided him the ambition to achieve anything that he put his mind to. Next, Stonewall Jackson was a compassionate man who felt as if it

Letter of advice on how customer service in BA can be improved Free Essays

I am writing to offer you some advice on how customer service in BA can be improved. Your Chief Executive, Mr Willie Walsh, suggested I write to you because he was impressed with my suggestions about monitoring and evaluating customer service. The four areas I will focus on are: 1. We will write a custom essay sample on Letter of advice on how customer service in BA can be improved or any similar topic only for you Order Now Improvements to quality 2. Reliability 3. Improvements to the organisation 4. Improvements to employees There are many ways in which you can improve the quality of your service in BA. Firstly I believe the introduction of extra staff training will highly benefit your company and in turn help improve your customer service. For instance all staff should be trained to deal with difficult customers; this can be very disruptive to the clientele and furthermore create a negative image for BA. If all staff is trained in this area it will mean that procedures can run smoothly and disruptive customers can be dealt with effectively. As well as this staff should be trained in helping people with special needs such as elderly, disabled, or young children. It is important that they are treated the same as regular customers and treated with due care and attention. This will attract attention to your company as people will know that your company is customer focused and has high levels of customer service for all types of people. Moreover you could introduce policies such as the introduction of new rules that will set higher expectations from your staff. This can include approaching as many customers as possible and asking them if they need any assistance in areas such as check-in. This will improve customer service levels as you can ensure that everyone is following the rules that have been set and in turn you can add more rules and regulations that will ensure that all staff is doing the same thing throughout your business. To each individual team you can set monthly targets, this will allow you to monitor the section and then create more objectives you plan for them to reach. This will benefit customers because each group of people will have objectives that they need to achieve and will be monitored throughout their progress to ensure the highest quality customer service is provided. As I suggested in a letter to your chief executive Mr Willie Walsh, the use of mystery shoppers and surveys will highly benefit your company in terms of customer service. These two methods will identify areas where there are problems and will allow you to put in the correct measures so this can be improved. For example if a mystery shopper identified that the staff were unfriendly, this will mean you can put in place training and/or aims and objectives and allow you to fix this issue. This will make your customer service more reliable because it will mean that it is aimed at certain aspects that have been pointed out as being under par. However it is also necessary for management to focus on customer service. This will help keep staff happy as they know that the management care about the service provided to customers and will in turn encourage them to adopt the same style. As well as this it can also improve levels of customer loyalty, this is because customers will feel that they are being treated very well and the staff are ensuring that the customer’s needs are met to the highest standard. This will not only boost the amount of return customers but also give BA the reputation of being customer focused. This will also attract customers that usually use other airlines increasing the popularity of your business and in turn the reputation of BA will grow. This will lead to increased sales as there will be a high volume of customers and consequently this will create increased profits. Finally I believe it is imperative that you train and develop your staff as this will allow you to gain the most from them. It will improve the levels of customer service they provide, and mean that they are more confident with their job roles. Secondly they will be motivated to work hard and self evaluate their performance. If each and every member of staff does this it will improve the whole of BA’s performance and make it become a more successful company. For instance if a member of staff has been trained in customer service, they will be confident when communicating with the customer and providing information (such as ticket information, baggage information), when they are positively rewarded by the customer (through language and expression) they will feel motivated to work even harder and will become critical of their own work and make sure it is to the best quality, and if not then try to improve it. This will mean that staff will constantly try to achieve the best that they can and provide excellent service. In comparison, a member of staff who has not been trained in customer service will be unsure about the way they should talk to the customer and will therefore feel unconfident with the work they are being asked to do. This will lead to them not being motivated to work hard which will make the quality of their work even worse. All in all this will mean that BA is being represented badly through its staff. How to cite Letter of advice on how customer service in BA can be improved, Papers

Chapter Solutions Tutorial Essay Example

Chapter Solutions Tutorial Paper Prom the chapter Scene Setter: Balance sheets and income statements are snapshots of your finances at a reticular moment. They dont capture your changing cash requirements through the yean Even the cash flow statement in your annual accounts is backward-looking, a summary of how your cash balance has changed over the last 12 months. While it can help you diagnose past problems, it cant help you anticipate future ones Many people think of cash as coins and notes. In accounting cash has a broader meaning. What type Of assets are defined as cash in accounting? In accounting the type of assets defined as cash include money, duplicates of credit card and Electronic Funds Transfer at Point Of Sale (EFFETE) sales, and any Other gettable instrument, such as a cheese or postal note, that a bank or financial institution will normally accept as a deposit to an account. After reading the concepts of a good system of internal control covered in this chapter, the owner of a small business was concerned that his internal control was not good. He counted the daily cash takings and prepared the deposit slip, and banked the takings intact each day. We will write a custom essay sample on Chapter Solutions Tutorial specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Chapter Solutions Tutorial specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Chapter Solutions Tutorial specifically for you FOR ONLY $16.38 $13.9/page Hire Writer He also approved payments and signed all cheeses. To overcome his problem, he decided he would have to hire more staff, so that he would be able to ensure adequate division of responsibility. Would this solve his problem? Explain. The basic purpose of any system of internal control is to safeguard the assets of the business and prevent fraud. In a small business where the management and owners are the same, there is virtually no risk of fraud the owners are unlikely to attempt to defraud themselves. Where owners have to delegate responsibility for control and management of business to employees, the need for a system to prevent or minimize fraud becomes more imperative. Another important aspect to keep in mind is that any system of internal control will involve costs. The more sophisticated the system becomes the more expensive it will be. It is essential to get the appropriate balance between the level of control and the costs to achieve that control. The system being used by the owner in the given circumstances is perfectly acceptable. To suggest the employment of more staff is merely to incur unnecessary costs with no real improvement in internal control. In fact, the employment to extra staff may in effect reduce the level of internal control already being achieved. Any system of internal control should be cost effective and be appropriate to the needs of the particular business. The principle that receipts should be banked daily and all payments made by cheese or electronic transfer provides a sound basis for internal control over cash. But it breaks down immediately when cash is given to a junior employee to spend through the petty cash fund. Discuss. An impress system Of petty cash should be used. Cash should not be available for employees to spend without verification or authentication. A voucher should always be prepared to validate 311 payments from the petty cash fund and receipts should be provided to the petty cashier to verify the amount spent where possible. Periodic checks should be made to verify tha t the cash on hand together with the vouchers issued is equal to the impress amount of the petty cash fund. Adequate petty cash records (e. G. Petty Cash Book) should be monitored. John Wiley Sons Australia, Ltd 2012 7. 3 Solutions Manual to accompany Accounting e by Hogget et al EXERCISE SOLUTIONS Exercise I C Composition of cash SOPHISTICATED COFFEE Required: What total dollar amount should be included in cash at 30 June? Explain how any items not included in cash should be reported in a balance sheet prepared on 30 June. 6. Currency and coin 5672 3. Cheeses dated 28-30 June 2164 Total included in cash 52 836 5. The 5300 OIL should be reported as a receivable from employees. 2. The $275 postdated cheese should be reported as an account receivable. . And 4. Would not be reported on a balance sheet. John Wiley sons Australia, Ltd 2012 Exercise 10. 3 Cash internal control procedures Explain briefly the significance of each of the following in a comprehensive system of control over cash transactions: With the segregation of cashiers duties from other functions, the cashier should not have access to the accounting records (other than cash journals). By segregating the duties of the cashier, any fraud will remain undetected only if the cashier colludes With Other members Of staff. This Will reduce the possibility of the cashier misappropriating funds and covering this up by altering the accounting records Without being found out. The daily banking principle means that all cash received must be banked daily intact. This will reduce the possibility of cash being misappropriated, as all the cash received is collected and banked in its entirety. Periodic checks are now possible, to ascertain that the cash banked (per bank deposit slip) agrees with he relevant source documents (receipts etc. ) and other records. The cash at bank account is balanced at various intervals (usually monthly). To ascertain that this balance actually represents the entitys cash balance at the bank or the amount owed to the bank, it has to agree with the amount shown on the bank statement at that date. The bank reconciliation links and confirms the cash records with a reliable outside authority the bank statement. If there are differences in the two records, the bank reconciliation will identify them, and records can be adjusted to take them into account. Under the impress system of petty cash, management allocates a certain float or retainer Of cash to be used for petty expenses. This float must be maintained from period to period until management revises it and allocates an increase in cash funds for petty expenses. The petty cashier uses the funds to meet petty expenses. When the fund is running low, the petty cashier is reimbursed the exact amount that was spent during the period bringing the float back to the original amount. This system allows management to control the maximum amount that can be pent on minor expenses. The impress system of petty cash supplements the control obtained by the general rule of banking all cash received intact and making all payments by cheese. Where it is impractical to write out cheeses for payments, the payments should be covered by a petty cash voucher (docket) and the control ensured by the use Of a fixed float. Cash budgets identify future cash inflows and outflows of the entity. By identifying the future expected cash flows management is better able to control and manage the entitys cash resources, e. G. Ewing able to meet ongoing ointments to creditors when they fall due, By identifying large expected cash outlays, management can plan for the payment of such expenditures through increasing cash inflows or by borrowing, Not being able to pay debts as they become due can have dire consequences for an entity even lead to its demise. A cash flow statement sets out the actual cash inflows and cash outflows of the entity over a period of time. The cash flows are clas sified in cash flows from operations, cash flows from investing activities, and cash flows related to financing.

Galapagos Islands essays

Galapagos Islands essays History, Environment and Description: Located in one of the most active volcanic regions on earth, the Galapagos are located on the Nazca Plate, close to its junction with the Cocos Plate. As are of the spreading of the sea floor (the movement of the plates in relation to each other) along the Galapagos Rift and the East Pacific Rise, the islands are moving south and eastward at a rate of more than 7 cm/yr., which may not seem fast but would, over a million years or so, amount to 70 km of movement! The evidence that the plate on which the islands sit is moving eastward is that the oldest islands are in the eastern part of the There is also volcanic activity where the western island is now. In fact, it is on these Western Islands where all the recent volcanic activity has occurred, while the Eastern Islands are the oldest. The "Hot Spot Theory" states that in certain places around the earth, there are more or less stationary areas of These hot spots cause the crust to melt in certain places and give rise to volcanoes. The Galapagos and Hawaiian Islands have mild volcanic eruptions where volcanic material comes out gently to form large lava flows The result is that the major Galapagos volcanoes tend to have smooth shield. Which were formed by explosive eruptions. The Galapagos archipelago consists of thirteen major islands, six minor islands and 40 some smaller rock formations and reefs spread out over 17,000 square miles of ocean. This cluster of Islands located on the equator are situated 600 miles off the coast of Ecuador. From the time they first broke through the ocean floor, some 7-9 million years ago, the Galapagos have remained a very active site of volcanic activity. The Average Temperature in August are 70*F and in September to ...

Amazing Sand Dollar Facts

Amazing Sand Dollar Facts A sand dollar (Echinarachnius parma) is an echinoid, a type of invertebrate animal whose skeletons- called tests- are commonly found on beaches the world over. The test is usually white or grayish-white, with a star-shaped marking in its center. The common name for these animals comes from their likeness to silver dollars. When they are alive, sand dollars look much different. They are covered with short, velvety spines that  are colored purple to reddish brown. Fast Facts: Sand Dollar Scientific Name: Echinarachnius parmaCommon Name(s): Common sand dollar or northern sand dollar; also known as sea cookies, snapper biscuits, sand cakes, cake urchins, or pansy shellsBasic Animal Group: InvertebrateSize: Live adult animals measure between 2–4 inches in diameter, and approximately 1/3 inch thick  Lifespan: 8–10 yearsDiet:  CarnivoreHabitat: Northern parts of the Atlantic and Pacific oceansPopulation: UnknownConservation Status: Not evaluated Description Living animals of the common sand dollar (Echinarachnius parma) species are generally sub-circular, measuring approximately 2–4 inches across, and are coated with spines that are purple, reddish-purple or brown in color. The test of the sand dollar is its endoskeleton- it is called an endoskeleton because it lies underneath the sand dollars  spines and skin, and it is made of fused calcareous plates. This is different than the skeletons of other echinoderms- sea stars, basket stars, and brittle stars have smaller plates that are flexible, and the skeleton of sea cucumbers is made up of tiny ossicles buried in the body. The top (aboral) surface of the sand dollar test  has a pattern that looks like five petals. There are five sets of tube feet that extend from these petals, which the sand dollar uses for respiration. The sand dollars anus is located at the rear of the animal- found in the edge of the test below the single vertical line extending from the center of the star. Sand dollars move by using the spines located on their underside.   Daniela Duncan / Getty Images Species Sand dollars are echinoderms, which means like sea stars, sea cucumbers, and sea urchins, they have a radiating arrangement of parts and a body wall stiffened by bony pieces such as spines. In fact, they are basically flat sea urchins and are in the same class, Echinoidea, as sea urchins. This class is divided into two groups: the regular echinoids (sea urchins and pencil urchins) and irregular echinoids (heart urchins, sea biscuits, and sand dollars). The irregular echinoids have a front, a back and basic bilateral symmetry on top of the normal pentameral symmetry (five parts around a center) that regular echinoids possess.   There are many species  of sand dollars. Besides E. parma, those found commonly in the United States include: Dendraster excentricus  (Eccentric, western, or Pacific sand dollar) are found in the Pacific Ocean from Alaska to Baja, California. These sand dollars grow to about 4 inches across and have gray, purple or blackish spines.Clypeaster subdepressus  (Sand dollar, sea biscuit) live in the Atlantic Ocean and the Caribbean Sea, from the Carolinas to Brazil.  Mellita sp. (Keyhole sand dollars or keyhole urchins) are found in tropical waters in the Atlantic, Pacific, and the Caribbean Sea. There are approximately 11 species of keyhole sand dollars. Sand dollars are classified as follows: Kingdom: AnimaliaPhylum: EchinodermataClass:  Clypeasteroida (includes sand dollars and sea biscuits) Habitat and Distribution Common sand dollars have been found throughout the North Pacific and eastern North Atlantic oceans, at locations from just below the intertidal zone to more than 7,000 feet.  As their name suggests, sand dollars prefer to live in the sand, in densities ranging between .5 and 215 per 10.7 square foot. They use their spines to burrow into the sand, where they seek protection and food.  Adult sand dollars- those over 2 inches in diameter- live in the intertidal zone. Most sand dollars live in seawater (saline environments), although some species do occur in estuarine habitats which combine of river and lake water, and are chemically distinct from saline or freshwater environments. Studies show that sand dollars require a certain level of salinity to fertilize their eggs. The sand dollar uses its spines to burrow into sand. Douglas Klug / Getty Images Diet and Behavior Sand dollars feed on small food particles in the sand, typically microscopically sized algae, but they do also eat fragments of other animals and have been classed as carnivores according to the World Register of Marine Species. The particles land on the spines, and then are transported to the sand dollars mouth by its tube feet, pedicellaria (pincers), and mucous-coated cilia. Some sea urchins rest on their edges in the sand to maximize their ability to catch prey that is floating by.   Like other sea urchins, the mouth of a sand dollar is called Aristotles lantern and is made up of five jaws. If you pick up a sand dollar test and shake it gently, you may hear the pieces of the mouth rattling inside. Reproduction and Offspring There are male and female sand dollars, although, from the outside, it is difficult to tell which is which. Reproduction is sexual and accomplished by the sand dollars releasing eggs and sperm into the water. The fertilized eggs are yellow in color and coated in a protective jelly, with an average diameter of about 135 micros, or 1/500th of an inch. They develop into tiny larvae, which feed and move using cilia. After several weeks, the larva settles to the bottom, where it metamorphoses. Juveniles (under 2 inches in diameter) are found in the subtidal zones and slowly migrate into exposed beach areas as they mature; the smallest are found in the highest beach elevations. They can bury themselves in the sand up to two inches deep, and very dense populations can stack themselves up to three animals deep. Threats Sand dollars may be affected by fishing, especially from bottom trawling, ocean acidification, which may affect the ability to form the test;  climate change, which might affect available habitat; and collection. Reduced salinity lowers fertilization rates. Although you can find plenty of information on how to preserve sand dollars, you should collect only dead sand dollars, never live ones. Sand dollars are not eaten by humans, but they can be prey for sea stars, fish, and crabs. Conservation Status The sand dollar is not currently listed as an endangered species. Sand Dollars and Humans Sand dollar tests are sold in shell shops and on the internet, for decorative purposes or souvenirs and often with a card or inscription referencing the  Legend of the Sand Dollar. Such references are associated with Christian mythology, suggesting that the five-pointed star in the center of the top of the sand dollars test is a representation of the Star of Bethlehem that guided the wise men to the baby Jesus. The five openings in the test are said to represent Jesuss wounds during his crucifixion: the four wounds in his hands and feet and the fifth in his side. On the underside of the sand dollar test, it is said that there is an outline of a Christmas poinsettia; and if you break it open, you will find five small bones that represent doves of peace. These doves are actually the five jaws of the sand dollars mouth (Aristotles lantern).   Other lore about sand dollars references the washed-up tests as mermaid coins or coins from Atlantis. Sources Allen, Jonathan D., and Jan A. Pechenik. Understanding the Effects of Low Salinity on Fertilization Success and Early Development in the Sand Dollar Echinarachnius Parma. The Biological Bulletin 218 (2010): 189–99. Print.Brown, Christopher L. Substrate Preference and Test Morphology of a Sand Dollar (Echinarachnius Parma) Population in the Gulf of Maine. Bios 54.4 (1983): 246–54. Print.Coulombe, Deborah. Seaside Naturalist: A Guide to Study at the Seashore. Simon Schuster, 1980..Echinarachnius parma (Lamarck, 1816). World Register of Marine Species.Echinarachnius parma (Lamarck 1816). Encyclopedia of Life.  Ellers, Olaf, and Malcolm Telford. Collection of Food by Oral Surface Podia in the Sand Dollar, Echinarachnius Parma (Lamarck). The Biological Bulletin 166.3 (1984): 574–82. Print.Harold, Antony S., and Malcolm Telford. Substrate Preference and Distribution of the Northern Sand Dollar, Echinarachnius Parma (Lamarck). International Echinoderms Conference. Ed . Lawrence, J.M.: A.A. Balkema, 1982. Print. Kroh, Andreas. Clypeasteroida. World Echinoidea Database, 2013.Pellissier, Hank. Local Intelligence: Sand Dollars. The New York Times, January 8, 2011. Smith, Andrew. B. Skeletal morphology of sand dollars and their relatives. The Echinoid Directory. Waggoner, Ben. Introduction to the Echinoidea. University of California Museum of Paleontology, 2001.