TOEFL Q4: Sampling Bias

Directions

In this lesson, your tutor will help you go over question four from the TOEFL speaking test. Read the text below out loud with the tutor.

Sampling Bias

Statistical surveys are an important way of gathering information about large groups of people. However, some surveys do not include all of the members of a group. When this happens, it is called sampling bias. Sampling bias often occurs because a small number of survey methods are used. The main problem of sampling bias is that it often produces results that are incorrect.


Reading time: 45 seconds

Listening

Listen to a short lecture related to the reading.
Note to tutor: read the text to the student. The text is not presented to the student in the actual test.  

Now I want to tell you how sampling bias led to one embarrassing news story about the 1948 presidential election. On the night of the election, one newspaper wrote on its front page that Thomas Dewey was defeated President Truman in the election. The newspaper wrote this story before the votes were counted. How did the newspaper come up with this headline? It conducted a survey. The problem with the survey was that it was only done over the telephone. Back then, only rich people had telephones. And rich people were mo likely to vote for Due. But most people wanted to vote for Truman. Since they did not have telephones, they were not included in the survey. Because of this, the survey was completely wrong. President Truman won the election over Dewey by a huge margin.

Question

The professor explains sampling bias by giving one example. Explain the example and how it explains the concept of sampling bias.


Preparation time: 30 seconds l Response time: 60 seconds

Summarize

Use the chart below to explain the main idea and the key points of the lecture.

Guideline
Topic The main idea of the lecture is the __
Detail 1 The professor explains that one newspaper incorrectly wrote that Dewey __ in the election. The newspaper wrote this story based on a __.
Detail 2 The survey was done __, so it only included rich people. These people were more likely to __. Therefore, the survey results were __.

Synthesize

Give a brief spoken response to the questions based on the announcement and the conversation.

  1. What is the main problem with sampling bias?
    •   The main problem with sampling bias is that it produces __. 
  2. What was the survey method talked about in the lecture?
    • The survey method talked about in the lecture was __.
  3. How did this survey method affect the results of the survey?
    • This method affected the results by including only __.

Sample Answer

Reading great sample answers is one way to improve. Go over the sample answer with your tutor. Ask questions if you have any.

Sample Answer
The professor explains the sampling bias through one embarrassing news story. Sampling bias is when a survey does not include a certain group of people. It usually creates a skewed results. To explain sampling bias, the professor talks about the 1948 presidential election. He explains that one newspaper said that Thomas Dewey beat President Truman in the election. This story was based on a survey that was conducted over telephone. At that time, only rich people had phone and they were more likely to vote for Dewey. Consequently, the result of the survey was completely wrong.

Further Study

Got more time? Here is a list of common vocab words related to the text you studied today. Go over each one with your tutor.

Additional Expressions
survey (n) a collection of opinions that represents the opinions of many
e.g. The survey found/revealed some surprising tendencies among the population.
produce (v) to bring forth; to develop
e.g. He has produced many albums.
election (n) the act of choosing a leader
e.g. a presidential/gubernatorial election
vote (v) to decide on a leader
e.g. Citizens will vote today for their new governor.
gather (v) to bring things together into a group; to collect
e.g. The children gathered their toys (together) and put them away.
headline (n) the title of a newspaper article
e.g. The story of his arrest appeared beneath the headline “Caught!”
include (v) to put in a group; to contain
e.g. Admission to the museum is included in the tour package.
conduct (v) to carry out; to control
e.g. scientists conducting research/experiments
poll (n) an activity in which several or many people are asked a question or a series of questions in order to get information about what most people think about something
e.g. A recent poll shows a decrease in the number of teenagers who smoke.
margin (n) an extra amount
e.g. a safety margin
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