Sampling Bias Reading Answers
The reading section of IELTS analyzes how proficient students are in reading and understanding English. With the IELTS exam, candidates' skills are assessed in reading, writing, speaking and listening. The IELTS reading section includes 40 questions of different types. The IELTS Academic reading section of the IELTS tests students’ effectiveness in reading skills through the given passage and their accurate response to the corresponding questions. Candidates can consider preparing using IELTS Reading Sample Papers for the IELTS test. The inclusion of the IELTS reading passage on Sampling Bias Reading Answers includes three types of questions as follows:
- True or False or Not Given
- Complete the Web Chart
- Multiple Choice Questions (MCQ)
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Section 1
Read the Passage to Answer the Following Questions
Sampling Bias Reading Answers
- Our primitive ancestors left many paintings on the walls inside caves. Additionally, inside and near these places there is evidence of re pits, and refuse and burial sites. However, one could equally imagine this same evidence of daily life on exposed cliffs or hillsides, on trees or animal skins, and beside rivers and coastlines. Such evidence, if it existed, would have long been washed, eroded, or rotted away. Thus, prehistoric people are characterized as ‘cavemen’, presumed to have a predilection for dwelling in these places only because that is where most evidence is taken. This ‘caveman effect’ is an example of what is known as ‘sampling bias’ — one of the biggest problems when conducting any form of statistical data gathering.
- Surveys, for example, are popular because they are easy to administer and relatively costeffective, particularly if conducted remotely through technical means, such as telephone, mail, email, or the Internet. Surveys also lend themselves to obtaining particularly large numbers of respondents, which, in theory, allows a greater chance of sampling all the variations of the target population. They can also be standardised with xed questions and responses (such as ‘tick the box’ or ‘closed-ended' questions). This allows easy collation, analysis, and presentation of results, all with the air of precision that mathematics brings. Such surveys, however, have proven notoriously unreliable because of the difculty in obtaining representative samples. In other words, the sampling is biased, or skewed in favour of certain outcomes.
- Let us look at some examples. If one calls people on cellphones, it immediately excludes those who favour landlines, and thus the sample of respondents may be those who are more technically-conversant, skewing data based on, say, technical issues (‘How often do you use the Internet?’). If one rings domestic homes during the daytime, most of those who work during the day will be excluded. Those that answer will more likely be the unemployed, disabled, elderly, and retired, skewing data based on, say, work-related issues (‘How important is work in your life?’). No matter how large the sampling size is, sampling bias can immediately invalidate the results.
- One of the more subtle of sampling biases is known as self-selection. No matter how rigorously the respondents are chosen to be random and characteristic of the target population, those who choose to respond will be different to those who do not. Generally, respondents who are willing to invest time in giving answers obviously want to say something, whereas those who choose not to answer probably do not. Thus, any survey in which many respondents do not answer, do not give clear answers, or only give cursory or unthinking answers, is immediately invalidated, since opinionated perspectives are disproportionately represented.
- The latter is such an immediate and obvious problem that it has given rise to techniques to maximise the possibility of garnering responses. One of the more effective is to give the respondents advanced warning (often through the mail), highlighting the time, the nature of the survey, and the mode of delivery, as well as expressing appreciation for the assistance. The interviewers themselves must be sufficiently trained in correct question-asking techniques, and, with cranks, salespeople, and scam-artists abounding, interviewers must provide introductions about themselves, their company, and the nature of the interview, fully and with evident sincerity, in order to gain the trust of those they are talking to.
- Even with this, sampling bias can easily arise due to the number of variables in place, since it only takes one to skew the data. If taking samples from a specic location — say, a street corner—then it may be that this location is in the business district, excluding ordinary workers from the sample. It may be that it is near a restaurant district, excluding those who cook more often for themselves. If there is a health club nearby, the majority of respondents may be much healthier than the average of the population. If it is on a university campus, designed to poll university students, is it near the engineering or the arts faculty? The part-time or full-time schools? Are they rich or poor? Male or female? What about race, colour, gender, religion, socio-economic background, and first language? The list goes on and on.
- One method to deal with this is to make sure all targeted groups are represented, if only a little, and make mathematical extrapolations to correct the bias. For this to work, the degree of underrepresentation needs to be quantied exactly, and one needs to assume the underrepresented respondents are indeed typical of their kind. If, for example, one aims to nd the opinion of the population regarding the outcome of an election, but could only, for whatever reasons, interview one woman for every four men, the responses of the women could be multiplied by four, and thus, one can assume (guardedly and with many provisos), that the sampling bias from gender has been corrected. But that does assume all the other variables which introduce bias have been excluded — often a very problematic assumption to make.
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Section 2
Solution and Explanation
Questions 14 to 18:
Write an answer in boxes from 14 to 18 by using:
- True: if the statement matches with the writer's point of view
- False: if the opinion of the writer contradicts the statement
- Not Given: if there is no information about the statement
Question 14. Cavemen were often very good artists.
Answer: Not Given
Supporting Sentence: Our primitive ancestors left many paintings on the walls inside caves
Keywords: primitive, paintings
Keyword Location: Para A, line 1
Explanation: the passage includes the statement that our primitive ancestors left many paintings while they lived in the caves, there is no mention of them being good artists in the passage.
Question 15. Surveys can be done cheaply by telephone.
Answer: True
Supporting Sentence: Surveys, for example, are popular because they are easy to administer and relatively cost - effective, particularly if conducted remotely through technical means, such as telephone,
Keywords: surveys, popular, easy to administer, relatively cost - effective, if conducted remotely, through technical means, telephone
Keyword Location: Para B lines 1-2
Explanation: Through the above statement it is clear that surveys are cheap when done by telephone.
Question 16. Surveys can usually give reliable information.
Answer: False
Supporting Sentence: Such surveys, however, have proven notoriously unreliable because of the difficulty in obtaining representative samples.
Keywords: surveys, proven notoriously, unreliable, difficulty, obtaining samples
Keyword Location: Para B lines 7-9
Explanation: The surveys conducted are mostly unreliable and it is evident from the information provided to us on line 5 of paragraph B.
Question 17. The elderly and disabled people are often at home during the day.
Answer: True
Supporting Sentence: Those that answer will more likely be the unemployed, disabled, elderly, and retired, skewing data based on, say, work-related issues.
Keywords: likely, unemployed, disabled, elderly and retired
Keyword Location: para C, lines 5-7
Explanation: The question matches with the supporting sentence which says elderly and disabled people stay at home.
Question 18. Larger survey samples can reduce sampling bias.
Answer: False
Supporting Sentence: This allows easy collation, analysis, and presentation of results, all with the air of precision that mathematics brings.
Keywords: easy collation, analysis, presentation, results, an air of precision, mathematics brings
Keyword Location: Para B, lines 6-7
Explanation: Larger survey samples create more bias, that's why the mathematical calculation is brought into account. Through paragraph B of the passage we get an idea of contradiction in viewpoint.
Questions from 19 to 24:
Write answers using no more than two words in the answer box given from 19 to 24.
- ________ Sampling bias
Answer: self-selection
Supporting Sentence: One of the more subtle of sampling biases is known as self-selection.
Keywords: more subtle, sampling biases, self-selection
Keyword Location: Para D, line 1
Explanation: Through the question, the author is trying to seek the information as to what should be the other name of sampling bias. So, the answer is self-selection in this case.
- _____ are over-represented
Answer: Opinionated perspectives
Supporting Sentence: only give cursory or unthinking answers, is immediately invalidated, since opinionated perspectives are disproportionately represented
Keywords: opinionated, prescriptions, disproportionately represented.
Keyword Location: para D last lines
Explanation: opinionated perspectives fit as an answer because it suggests the perspective is sometimes over-represented. The information is provided to us, in the last line of paragraph D.
- need to _____ number of responses.
Answer: Maximize (the)
Supporting Sentence: The latter is such an immediate and obvious problem that it has given rise to techniques to maximize the possibility of garnering responses
Keywords: immediate, obvious problem, rise to techniques, maximize, the possibility of garnering responses
Keyword Location: In paragraph E, lines 1-2
Explanation: the information regarding techniques gives rise to a number of responses. So, the answer is to maximize which leads to maximizing the possibility of garnering responsibility.
- ensure interviewers are ________
Answer: sufficiently trained
Supporting Sentence: he interviewers themselves must be sufficiently trained in correct question-asking techniques, and, with cranks, salespeople, and scam-artists abounding, interviewers must provide introductions about themselves,
Keywords: interviewers themselves, sufficiently trained, correct, question-asking techniques
Keyword Location: Para E, lines 4-6
Explanation: To ask the correct question, the interviewers need a technique and only sufficient training can provide them such supremacy.
- give complete and honest ___
Answer: introduction
Supporting Sentence: interviewers must provide introductions about themselves, their company, and the nature of the interview, fully and with evident sincerity,
Keywords: provide introductions, their company, nature of the interview, fully and with evident, sincerity
Keyword Location: Para E, last 3 lines
Explanation: Giving an honest and unbiased introduction in your interview is representative of reliable information. Not only the introduction but providing complete information leads to getting more approval.
- to build ___
Answer: trust
Supporting Sentence: interviewers must provide introductions about themselves, their company, and the nature of the interview, fully and with evident sincerity, in order to gain the trust of those they are talking to.
Keywords: interviewers, introduction about themselves, with evident sincerity, to gain, trust, they are talking to
Keyword Location: Para E, last 3 lines
Explanation: The good start with proper introduction leads to the building of trust in information provided by the interviewers.
Questions from 25 to 26:
Choose the best suitable answer from the options given below each statement. Write the answer in the box from 25 to 26.
- The number of sampling variables
- is usually not so large.
- can result in important input being lost.
- means many locations need to be used.
- can result in lists being necessary.
Answer: B
Supporting Sentence: Even with this, sampling bias can easily arise due to the number of variables in place, since it only takes one to skew the data.
Keywords: sampling bias, number of variables, takes one to skew
Keyword Location: Para F lines 1-2
Explanation: When a large number of sampling variables are taken into consideration, then there is certainly a loss of information.
- Mathematical extrapolation
- can yield confident results.
- requires responses from both men and women.
- needs exact ratios.
- needs many respondents.
Answer: C
Supporting Sentence: mathematical extrapolations to correct the bias. For this to work, the degree of underrepresentation needs to be quantified exactly,
Keywords: mathematical extrapolation, the bias, degree of underrepresentation, to be quantified exactly
Keyword Location: Para G lines 1-2
Explanation: Mathematical extrapolation is the method to correct the bias. In paragraph G, the author has talked about this concept. It seems appropriate to choose option B, as per the information given.
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