/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 33 Refer to the following story: An... [FREE SOLUTION] | 91Ó°ÊÓ

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Refer to the following story: An orange grow. er wishes to compute the average yield from his orchard. The orchard contains three varieties of trees: \(50 \%\) of his trees are of variety \(A, 25 \%\) of variety \(B,\) and \(25 \%\) of variety \(C\) (a) Suppose that the grower samples randomly from 300 trees of variety A, 150 trees of variety \(B\), and 150 trees of variety C. What type of sampling is being used? (b) Suppose that the grower selects for his sample a 10 by 30 rectangular block of 300 trees of variety \(A\), a 10 by 15 rectangular block of 150 trees of variety \(B\), and a 10 by 15 rectangular block of 150 trees of variety \(\mathrm{C}\). What type of sampling is being used?

Short Answer

Expert verified
The type of sampling used in part (a) is stratified sampling, while in part (b) it is cluster sampling.

Step by step solution

01

Identifying the Sampling Method in (a)

In part (a), the grower selects a fixed number of trees from each variety: 300 trees of variety A, 150 trees of variety B, and 150 trees of variety C. This sampling is proportional to the percentage of each variety in the orchard. Since the grower samples a proportion of trees based on their representation in the population, this method is known as stratified sampling.
02

Identifying the Sampling Method in (b)

In part (b), the grower selects sample trees by choosing rectangular blocks of trees within each variety. This method does not rely on random selection but on the geographic clustering of trees. As the grower is selecting blocks of trees, this method is an example of cluster sampling.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Stratified Sampling
Imagine wanting to understand the diversity of a garden with various flowers. Stratified sampling would involve dividing the garden into sections based on flower types, then selecting samples from each section to accurately represent the whole garden.

This method is beneficial when dealing with populations that have distinct subgroups, like the orange grove with different varieties of trees (A, B, and C). By ensuring each variety is represented proportionally in the sample, like the grower sampling 300 trees from variety A and 150 from B and C, we get a more accurate picture of the entire orchard's yield. This 'miniaturized view' retains the diversity of the population, crucial when the subgroups differ significantly in their characteristics.

In terms of educational content, if a student were to conduct research in a school with different academic programs, using stratified sampling would mean collecting data from each program proportionally to their size within the school. This would provide an accurate reflection of the entire school's academic performance.
Cluster Sampling
Now, let's say our garden is vast, making it challenging to reach every flower type. Cluster sampling solves this problem by selecting random but naturally occurring groups, or 'clusters', and then surveying all the flowers within those clusters. In the case of the orange grove, the grower took rectangular blocks of trees as clusters to sample from.

This approach is like dividing a large dining table into sections and only sampling the dishes in one or two areas. It simplifies sampling when individual random selection may be too time-consuming or costly. However, if clusters are not representative, it can lead to biases. It's like assuming the taste of all the food at the table based on just sampling the bread and salad in your corner.

For students, imagine a teacher wants to understand classroom behavior but can't observe every class. By selecting a few classrooms as clusters and observing them in full, the teacher might infer the general behavior patterns in the school. Just remember that each classroom (cluster) should provide a mini-picture of the school's overall behavior for this to be effective.
Statistics in Agriculture
Utilizing statistics in agriculture, such as in our orange orchard, is about using data to improve yields, manage resources, and anticipate issues. It's like being a detective scrutinizing clues to solve the mystery of 'What makes a healthy, productive farm?'

Sampling methods are the tools helping to gather those clues without examining every single plant. It's practical, like using a recipe to predict how a large cake will taste by only sampling a small piece. By looking at specific samples of crops or trees, farmers can estimate overall harvests, disease spread, or the effectiveness of fertilizers, guiding their decisions for the entire farm.

For illustrative purposes, a student's science project might involve understanding the health of a local park's ecosystem. They could apply statisitical methods, drawing conclusions about the park's plant and animal life without needing to catalogue every leaf and critter.
Proportional Sampling
Proportional sampling is like cutting a miniature cake from a large one and ensuring all the layers and flavors are represented in the smaller piece. In our grove story, the orange grower applies this by sampling trees in the same ratio as their presence within the entire orchard. It's a fair approach that mirrors the actual composition.

This method ensures that the different categories (in our case, varieties of trees) in the population are not just included but included in correct proportions. It avoids over-representing one type of tree while under-representing another which could skew the data and lead to incorrect conclusions about the average yield of the orchard.

For students learning about surveys or research, proportional sampling would mean ensuring all groups within a population, like different student organizations, are included in a study relative to their actual sizes. This helps to justly measure opinions or behaviors, capturing a true snapshot of the whole.

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Most popular questions from this chapter

To estimate the population in a rookery, 4965 fur seal pups were captured and tagged in early August. In late August. 900 fur seal pups were captured. Of these, 218 had been tagged. Based on these figures, estimate the population of fur seal pups in the rookery. [Source: Chapman and Johnson, "Estimation of Fur Seal Pup Populations by Randomized Sampling." Transactions of the American Fisheries Society. 97 (July 1968\(), 264-270 .\)

You are a fruit wholesaler. You have just received 250 crates of pineapples: 75 crates came from supplier \(A, 75\) crates from supplier \(\mathrm{B}\), and 100 crates from supplier \(\mathrm{C}\). You wish to determine if the pineapples are good enough to ship to your best customers by inspecting a sample of \(n=20\) crates. Describe how you might implement each of the following sampling methods. (a) Simple random sampling (b) Convenience sampling (c) Stratified sampling (d) Ouota sampling

Refer to the following story: The manufacturer of a new vitamin (vitamin \(X\) ) decides to sponsor a shudy to determine the vitamin's effectiveness in curing the common cold. Five hundred college students having a cold were recruited from colleges in the San Diego area and were paid to participate as subjects in this study, The subjects were each given two tablets of vitamin \(X\) a day. Based on information provided by the subjects themselves, 457 of the 500 subjects were cured of their colds within 3 days. (The average number of days a cold lasts is 4.87 days.) As a result of this study, the mamufacturer launched an advertising campaign based on the claim that "vitamin \(X\) is more than \(90 \%\) effective in curing the common cold." (a) Describe as specifically as you can the target population for the study. (b) Describe the sampling frame for the study. (c) Describe the sample used for the study.

Refer to a landmark study conducted in 1896 in Denmark by Dr. Johannes Fibiger, who went on to receive the Nobel Prize in Medicine in \(1926 .\) The purpose of the study was to determine the effectiveness of a new serum for treating diphtheria, \(a\) common and often deadly respiratory disease in those days. Fibiger conducted his shudy over a one-year period (May 1896 April 1897 ) in one particular Copenhagen hospital. New diphtheria patients admilted to the hospital received different treatments based on the day of admission. In one set of days (call them "even" days for convenience), the patients were treated with the new serum daily and received the standard treatment. Patients admitted on alternate days (the "odd" days) received just the standard treatment. Over the one-year period of the study, eight of the 239 patients admitted on the "even" days and treated with the serum died, whereas 30 of the 245 patients admitted on the "odd" days died. (a) Describe the sample for Fibiger's study. (b) Is selection bias a possible problem in this study? Explain.

An article in the Providence Jourmal about automobile accident fatalities includes the following observation: "Fortytwo percent of all fatalities occurred on Friday, Saturday, and Sunday, apparently because of increased drinking on the weekends." (a) Give a possible argument as to why the conclusion drawn may not be justified by the data. (b) Give a different possible argument as to why the conclusion drawn may be justified by the data after all.

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