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Production Time A supervisor of a large factory takes a random sample of 100 laborers from the factory database. He calculates the mean time taken by them to produce one unit of the product. He records this value and repeats the process: He takes another random sample of 100 laborers and calculates the mean time taken. After he has done this 500 times, he makes a histogram of the mean time taken. Is this histogram a display of the population distribution, the distribution of a sample, or the sampling distribution of means?

Short Answer

Expert verified
The histogram represents the sampling distribution of means.

Step by step solution

01

Identify the Data

In this scenario, the data being collected is the average time taken by 100 workers, randomly selected, to produce one unit of the product. This process is repeated 500 times, hence we have 500 different means.
02

Identify the nature of the Process

The process involves repeated random sampling of the same size and calculation of the mean from each sample. This process describes a method of creating a sampling distribution. The process does not relate to population or sample distribution.
03

Classify the Histogram

Considering the nature of the data collection process, the histogram ... is a display of the sampling distribution of means.

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Key Concepts

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

Histogram
A histogram is an incredibly useful tool in statistics that helps us visualize data. In its simplest form, a histogram displays the frequency of a data set's outcomes as bars. This allows viewers to easily see the distribution, center, and spread of the data.
When creating a histogram, the data is divided into intervals or "bins." The height of each bar represents the number of data points (or frequency) falling within that interval. In the context of the original exercise, the supervisor used a histogram to represent the mean time taken by different samples of workers.
  • Helps to understand the shape of the data distribution.
  • Enables identification of central tendencies and variations.
  • Essential for summarizing large data sets in an easy-to-read format.
A histogram provides a visual summary of the data, which makes it easier to interpret complex data sets like those of repeated means.
Random Sampling
Random sampling is a statistical method used to ensure that each member of a population has an equal chance of being selected for a sample. This technique aims to make the sample representative of the population as a whole.
In the original exercise, the supervisor takes random samples of 100 laborers each time he conducts this process. This ensures that the calculated mean times aren't biased by any particular subset of workers.
  • Minimizes selection bias.
  • Increases the reliability of statistical inferences.
  • Key to creating effective sampling distributions.
Random sampling is crucial for conducting experiments that aim to generalize findings from the sample to the larger population.
Distribution of Means
The distribution of means, also known as the sampling distribution of the sample mean, is a critical concept in statistics. It refers to the distribution you get by taking the means of multiple random samples from a population.
In the exercise, the supervisor calculated the mean production time from 100 workers for each of the 500 samples. These sample means create their own distribution.
  • This distribution tends to be normal due to the Central Limit Theorem.
  • Has a smaller standard deviation compared to individual sample data.
  • Converges to the true population mean with fairly large sample sizes.
The distribution of means provides insights into doing inferential statistics, helping to make conclusions about population parameters.
Statistical Sampling Method
Statistical sampling methods are approaches used to select samples from a larger population for statistical study. These methods aim to obtain samples that accurately reflect the population being studied.
In this exercise, the statistical sampling method used was random sampling, which is a type of probability sampling. There were repeated samplings of the same size (100 workers), and for each sampling, an average production time was calculated.
  • Ensures each sample reflects the diversity of the population.
  • Minimizes systematic errors.
  • Core aspect of conducting reliable and valid research.
Different statistical sampling methods offer various advantages and can be chosen based on the research objectives and the availability of resources.

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Most popular questions from this chapter

Exam Scores The distribution of the scores on a certain exam is \(N(70,10)\), which means that the exam scores are Normally distributed with a mean of 70 and standard deviation of \(10 .\) a, Sketch the curve and label, on the \(x\) -axis, the position of the mean, the mean plus or minus one standard deviation, the mean plus or minus two standard deviations, and the mean plus or minus three standard deviations. b. Find the probability that a randomly selected score will be between 50 and 90 . Shade the region under the Normal curve whose area corresponds to this probability.

Used Car Ages (Example 5) The mean age of all 638 used cars for sale in the Ventura Country Star one Saturday in 2013 was \(7.9\) years, with a standard deviation of \(7.7\) years. The distribution of ages is right-skewed. For a study to determine the reliability of classified ads, a reporter randomly selects 40 of these used cars and plans to visit each owner to inspect the cars. He finds that the mean age of the 40 cars he samples is \(8.2\) years and the standard deviation of those 40 cars is \(6.0\) years. a. Which of these four numerical values are parameters and which are statistics? b. \(\mu=? \sigma=? s=? \bar{x}=?\) c. Are the conditions for using the CLT fulfilled? What would be the shape of the approximate sampling distribution of a large number of means, each from a sample of 40 cars?

Choose a test for each situation: one-sample \(t\) -test, twosample \(t\) -test, paired \(t\) -test, and no \(t\) -test. a. A researcher goes to a clothing store and observes whether each person is male or female and whether they return the clothes to the correct racks (yes or no) after trying them on. b. A random sample of restaurants is obtained. Then the researcher walks into each restaurant wearing ordinary clothes and finds out how long it takes (in minutes) for a waiter to approach the researcher. Later, the researcher goes into the same restaurant dressed in expensive clothes and finds out how long it takes for a waiter to approach. c. The supervisor observes the number of working hours of a random sample of part-time workers and a random sample of regular workers.

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GPAs (Example 11) In finding a confidence interval for a random sample of 30 students GPAs, one interval was \((2.60,3.20)\) and the other was \((2.65,3.15)\). a. One of them is a \(95 \%\) interval and one is a \(90 \%\) interval. Which is which, and how do you know? b. If we used a larger sample size \((n=120\) instead of \(n=30\) ). would the \(95 \%\) interval be wider or narrower than the one reported here?

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