Questions and Answers
What is the difference between an observational study and an experiment?
In an experiment, a treatment is applied to part of a population and responses are observed. In an observational study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions.
What is the difference between a census and a sampling?
A census includes the entire population. A sampling includes only part of the population.
What is the difference between a random sample and a simple random sample?
With a random sample, each individual has the same chance of being selected. With a simple random sample, all samples of the same size have the same chance of being selected.
What is replication in an experiment? Why is replication important?
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A placebo is an actual treatment.
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A double-blind experiment is used to increase the placebo effect.
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Using a systematic sample guarantees that members of each group within a population will be sampled.
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The method for selecting a stratified sample is to order a population in some way and then select members of the population at regular intervals.
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Determine whether the study is an observational study or an experiment: In a survey of 1356 adults in a country, 53% said the country's leader should release all medical information that might affect their ability to serve. Explain.
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Determine whether the study is an observational study or an experiment: To study the effects of social media on teenagers' brains, researchers showed a few dozen teenagers photographs that had varying numbers of 'likes' while scanning the reactions in their brains. Explain.
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Use the row of numbers shown below to generate 12 random numbers between 01 and 99. Starting at the beginning of the row, what are the first 12 numbers between 01 and 99 in the sample? 79012 08168 50961 54503 28043 50955 36294
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What technology format could be used to generate twelve random numbers between 1 and 750?
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A pharmaceutical company wants to test the effectiveness of a new allergy drug. Describe the experimental units and treatment.
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What type of sample was used in the 1965 study using random digit dialing to call 1200 people?
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Study Notes
Observational Studies vs. Experiments
- In an experiment, a treatment is applied to a portion of a population, allowing researchers to observe responses.
- An observational study involves measuring characteristics without altering existing conditions.
Census vs. Sampling
- A census encompasses the entire population.
- Sampling consists of selecting only a segment of the population for study.
Random Sample vs. Simple Random Sample
- A random sample gives each individual in the population an equal chance of being selected.
- A simple random sample ensures that all possible samples of the same size have an equal chance of selection.
Replication in Experiments
- Replication refers to repeating an experiment under consistent conditions.
- It is crucial for enhancing the validity and reliability of results.
Placebo Definition
- A placebo is not an actual treatment; it is a fake treatment designed to simulate a real one.
Double-Blind Experiment
- A double-blind experiment aims to reduce the placebo effect by ensuring neither the participants nor the researchers know who receives the actual treatment.
Stratified Sample vs. Systematic Sample
- A stratified sample ensures representation from each group within a population.
- A systematic sample involves ordering the population and selecting members at regular intervals.
Observational Study Example
- A survey of 1356 adults concerning opinions on medical information related to their leaders is observational, as it does not involve a treatment manipulation.
Experiment Example
- An experiment studying the effects of social media on teenagers' brains uses treatments (photographs with varying likes) and records reactions, thus qualifying it as an experiment.
Generating Random Numbers
- A method to extract random numbers from a given row involves sequentially selecting two-digit numbers within a specified range.
Technology for Random Number Generation
- The function
RandInt(1,750,12)can generate twelve random integers between 1 and 750.
Allergy Drug Experiment
- The experimental units in the allergy drug trial are females aged 30-35.
- There is potential researcher bias if the researcher knows which subjects received the drug vs. placebo.
- The study becomes a double-blind study if neither the researcher nor the participant is aware of who received the actual treatment.
Random Digit Dialing Method
- Random digit dialing involved a simple random sampling technique, allowing for equal chance of selection across all phone numbers dialed, ensuring each had the same likelihood of being included in the study.
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Description
Test your understanding of key concepts in statistics with these flashcards covering observational studies, experiments, censuses, and sampling. Perfect for students seeking to reinforce their knowledge from Chapter 1.3.
