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Questions and Answers
What is an experiment?
What is an experiment?
An experiment is a study in which participants are randomly assigned to different conditions to determine the effect of manipulated variables.
Is the following an experiment or an observational study? In the study to examine whether planting trees reduces air pollution, trees were planted in half of the sampled city blocks.
Is the following an experiment or an observational study? In the study to examine whether planting trees reduces air pollution, trees were planted in half of the sampled city blocks.
Experiment
Do the following data come from an experiment or an observational study? The study of the ACTN3 gene and its association with sprinting ability.
Do the following data come from an experiment or an observational study? The study of the ACTN3 gene and its association with sprinting ability.
Observational study
Does the study measuring the impact of music volume on beer consumption provide evidence that louder music causes people to drink more beer?
Does the study measuring the impact of music volume on beer consumption provide evidence that louder music causes people to drink more beer?
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Which study provides better evidence that nut consumption reduces LDL cholesterol?
Which study provides better evidence that nut consumption reduces LDL cholesterol?
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Is the headline 'Antibiotics in infancy may cause obesity in adults' an appropriate conclusion based on the studies for mice and humans?
Is the headline 'Antibiotics in infancy may cause obesity in adults' an appropriate conclusion based on the studies for mice and humans?
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In the study about green spaces making kids smarter, what are the cases?
In the study about green spaces making kids smarter, what are the cases?
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In the green spaces study, what is the explanatory variable?
In the green spaces study, what is the explanatory variable?
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In the study about late-night eating, is the explanatory variable categorical or quantitative?
In the study about late-night eating, is the explanatory variable categorical or quantitative?
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Can we conclude that eating late at night worsens some typical effects of sleep deprivation?
Can we conclude that eating late at night worsens some typical effects of sleep deprivation?
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In the study about beauty sleep, what is the response variable?
In the study about beauty sleep, what is the response variable?
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Is the study about beauty sleep an experiment or an observational study?
Is the study about beauty sleep an experiment or an observational study?
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Is the following variable categorical or quantitative? People in a city are asked if they support a new recycling law.
Is the following variable categorical or quantitative? People in a city are asked if they support a new recycling law.
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Is the following variable categorical or quantitative? Record the percentage change in the price of a stock for 300 stocks publicly traded on Wall Street.
Is the following variable categorical or quantitative? Record the percentage change in the price of a stock for 300 stocks publicly traded on Wall Street.
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Is the following variable categorical or quantitative? Collect data from a sample of teenagers with a question that asks 'Do you eat at least five servings a day of fruit and vegetables?'
Is the following variable categorical or quantitative? Collect data from a sample of teenagers with a question that asks 'Do you eat at least five servings a day of fruit and vegetables?'
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Is the following variable categorical or quantitative? Record whether or not the literacy rate is over 90% for each country in the world.
Is the following variable categorical or quantitative? Record whether or not the literacy rate is over 90% for each country in the world.
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Number of years smoking cigarettes is the?
Number of years smoking cigarettes is the?
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Yield of the crop is?
Yield of the crop is?
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BAC is the?
BAC is the?
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Is the variable whether or not the spider engaged in mock sex categorical or quantitative?
Is the variable whether or not the spider engaged in mock sex categorical or quantitative?
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Is the variable length of time for real mating categorical or quantitative?
Is the variable length of time for real mating categorical or quantitative?
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Is the variable length of time for real mating the explanatory variable or the response variable?
Is the variable length of time for real mating the explanatory variable or the response variable?
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Is estrogen concentration categorical or quantitative?
Is estrogen concentration categorical or quantitative?
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Is fertility level categorical or quantitative?
Is fertility level categorical or quantitative?
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How many cases are there in the dataset of rowing times?
How many cases are there in the dataset of rowing times?
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How many variables are there in this dataset of rowing times?
How many variables are there in this dataset of rowing times?
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Is the type of diet variable categorical or quantitative?
Is the type of diet variable categorical or quantitative?
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Is metabolic status of the daughters variable categorical or quantitative?
Is metabolic status of the daughters variable categorical or quantitative?
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Is metabolic status of the daughters the explanatory variable or the response variable?
Is metabolic status of the daughters the explanatory variable or the response variable?
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How many variables are mentioned in the elderly man's nose study description?
How many variables are mentioned in the elderly man's nose study description?
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How many variables are categorical? How many are quantitative?
How many variables are categorical? How many are quantitative?
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How many cases and how many variables are in the hand-washing study?
How many cases and how many variables are in the hand-washing study?
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Is the data for the trout recorded as a population or a sample?
Is the data for the trout recorded as a population or a sample?
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Is the data for the music website users a population or a sample?
Is the data for the music website users a population or a sample?
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Is the athletic participation questionnaire data a population or a sample?
Is the athletic participation questionnaire data a population or a sample?
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Does the sampling method used for drawing names from students produce a random sample?
Does the sampling method used for drawing names from students produce a random sample?
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Is the method described for selecting genes a random sample?
Is the method described for selecting genes a random sample?
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Does the sampling method for university students provide a random sample?
Does the sampling method for university students provide a random sample?
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Is the sampling method for CNN website visitors random?
Is the sampling method for CNN website visitors random?
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Is the method of data collection in the library poll biased?
Is the method of data collection in the library poll biased?
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Is the method of data collection for bruises on apples biased?
Is the method of data collection for bruises on apples biased?
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Is the method of data collection for printer performance biased?
Is the method of data collection for printer performance biased?
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Are the people who answered the work uniform poll likely to be representative of all adult workers?
Are the people who answered the work uniform poll likely to be representative of all adult workers?
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Is it reasonable to generalize that 24% of all adult workers would like to wear a uniform?
Is it reasonable to generalize that 24% of all adult workers would like to wear a uniform?
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Is the sample likely to be representative of all Canadian consumers?
Is the sample likely to be representative of all Canadian consumers?
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Is it reasonable to generalize this result to estimate that about 71% of all Canadian consumers regularly stream music?
Is it reasonable to generalize this result to estimate that about 71% of all Canadian consumers regularly stream music?
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Is the sample likely to represent all registered voters in Iowa?
Is the sample likely to represent all registered voters in Iowa?
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Is it reasonable to generalize this result to estimate that 65% of all registered voters in Iowa agree that the world needs to do more to combat climate change?
Is it reasonable to generalize this result to estimate that 65% of all registered voters in Iowa agree that the world needs to do more to combat climate change?
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What percent of people wash their hands after using the washroom based on observed behavior?
What percent of people wash their hands after using the washroom based on observed behavior?
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Why might there be a discrepancy in the percent from the telephone survey compared to the observed percent?
Why might there be a discrepancy in the percent from the telephone survey compared to the observed percent?
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Is the sample of 808 people likely to be representative of all US residents between ages 18 and 34?
Is the sample of 808 people likely to be representative of all US residents between ages 18 and 34?
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What population can we generalize from the findings of the NHANES study?
What population can we generalize from the findings of the NHANES study?
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What population can we generalize from the findings of the NHAMCS study?
What population can we generalize from the findings of the NHAMCS study?
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Which survey would probably address whether overweight people are more likely to develop diabetes?
Which survey would probably address whether overweight people are more likely to develop diabetes?
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Which survey would probably address the proportion of emergency room visits that involve sports-related injuries?
Which survey would probably address the proportion of emergency room visits that involve sports-related injuries?
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Which survey would probably address the difference in waiting time for male and female patients in the emergency room?
Which survey would probably address the difference in waiting time for male and female patients in the emergency room?
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Which survey would probably address the proportion of US residents who have visited an emergency room within the past year?
Which survey would probably address the proportion of US residents who have visited an emergency room within the past year?
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Is the claim 'Daily exercise improves mental performance' one of association and causation or only association?
Is the claim 'Daily exercise improves mental performance' one of association and causation or only association?
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Is the claim 'Among college students, no link found between number of friends on social networking websites and size of the university' one of association or causation?
Is the claim 'Among college students, no link found between number of friends on social networking websites and size of the university' one of association or causation?
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Is the claim 'Cell phone radiation leads to deaths in honey bees' one of association and causation or only association?
Is the claim 'Cell phone radiation leads to deaths in honey bees' one of association and causation or only association?
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Is the claim 'Cat owners tend to be more educated than dog owners' one of association only?
Is the claim 'Cat owners tend to be more educated than dog owners' one of association only?
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Is the claim 'Want to lose weight? Eat more fiber!' one of association and causation?
Is the claim 'Want to lose weight? Eat more fiber!' one of association and causation?
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Is the study investigating if eating brown rice affects metabolism an experiment or an observational study?
Is the study investigating if eating brown rice affects metabolism an experiment or an observational study?
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Study Notes
Categorical vs. Quantitative Variables
- Categorical variables represent categories or groups (e.g., public support for recycling laws, survey responses on eating habits).
- Quantitative variables express numerical values (e.g., stock price change percentages, time taken to row across the Atlantic).
- Examples include the percentage of fish eggs fertilized based on estrogen levels (quantitative) and literacy rates (categorical).
Explanatory and Response Variables
- Explanatory variables help clarify the cause (e.g., years smoking related to lung capacity).
- Response variables reflect outcomes influenced by explanatory variables (e.g., crop yield affected by fertilizer amount).
- In spider mating behavior, engagement in mock sex is categorical and the time to real mating is quantitative, making it a response variable.
Population vs. Sample
- A sample is a subset of a population (e.g., a fisherman weighing 5 fish) while the population includes all entities of interest (e.g., all trout in a lake).
- Different studies assess populations, such as a music site’s active users (population) versus respondents from a questionnaire (sample).
Validity of Sampling Methods
- Random samples are needed for trustworthy data across populations (e.g., randomly selected protein-coding genes).
- Non-random methods can introduce bias, as seen in surveys that only target certain demographics, such as visitors to a website.
Generalizability of Results
- Citizen polls may yield generalizable results if samples are correctly randomized (e.g., 71% of Canadian consumers streaming music).
- Poorly recruited participants (e.g., library students) may lead to biased conclusions about entire populations.
Association and Causation Interpretations
- Causation indicates a direct impact (e.g., exercise improving mental performance), while associations only suggest a relationship.
- Claims regarding effects of behaviors, such as fiber intake on weight loss or cell phone radiation on bee deaths, indicate causal relationships validated by studies.
Experimental vs. Observational Studies
- Experiments involve manipulation of variables (e.g., testing music volume in shops).
- Observational studies assess existing conditions without interference (e.g., genetic studies on sprinting ability).
- Both approaches provide insights, but only experiments can establish direct causal links.
Observations of Human Behavior
- Behavioral surveys often reveal discrepancies when compared to direct observations, such as self-reported hand-washing rates versus actual observed behavior.
- Public health studies can provide detailed insights upon systematic observation across varied locations or demographics.
Conclusion
- Understanding and distinguishing between variable types (categorical vs. quantitative), sampling techniques (population vs. sample), and study designs (experiment vs. observational) is essential for statistical analysis and drawing valid conclusions in research.### Nuts and Cholesterol
- Two studies examined nut consumption's impact on LDL cholesterol levels.
- Study 1 randomized participants into two groups: one consumed nuts daily, while the other did not.
- Study 2 allowed participants to self-report nut consumption without randomization.
- Both studies found a correlation between nut consumption and lower LDL cholesterol, but Study 1 offers stronger evidence.
Antibiotics in Infancy and Obesity in Adults
- A study involving mice linked early antibiotic use to increased obesity levels in adulthood.
- A human study indicated children treated with antibiotics in infancy were more prone to obesity later in life.
- Researchers suggest gut microbiome changes may contribute to this effect.
- The conclusion about obesity in mice is justified, while for humans, it is not as definitive.
Green Spaces Make Kids Smarter
- A study with 2,623 schoolchildren in Barcelona assessed the correlation between greenery around schools and cognitive performance.
- Increased vegetation was linked to better working memory and attention span in children.
- Study cases include the participating children, while the explanatory variable is the surrounding greenery.
- The response variable is measured cognitive performance.
- Headline implies causal inference; however, the observational nature of the study limits definitive conclusions.
Sitting is the New Smoking
- A significant study followed over 146,000 individuals and established a link between prolonged sitting and cancer risk in women.
- The explanatory variable, leisure time spent sitting, is quantitative, while the response variable, cancer incidence, is categorical.
- The 2015 study is observational; hence, causation cannot be established nor can we definitively rule it out.
Late Night Eating
- A controlled study evaluated the effects of late-night eating on cognitive performance due to sleep deprivation.
- Participants were split into groups: one with food access and the other fasting overnight.
- Those fasting showed better reaction times and attention, indicating late-night eating negatively impacts cognitive function.
- The explanatory variable (food access) is categorical, while response variables (reaction time and attention) are quantitative.
- This study is categorized as an experiment allowing for causal conclusions, but confounding variables are likely nonexistent.
To Spoon or Not to Spoon?
- Research involving 335 romantic partners revealed a correlation between cuddling time post-sex and increased sexual and relationship satisfaction.
- The study format is observational, meaning causation cannot be concluded.
- Headlines suggesting direct positive impacts of post-sex affection on satisfaction are not strongly supported by the evidence.
Urban Brains and Rural Brains
- A 2010 study found city residents have higher risks of anxiety (21%) and mood disorders (39%) compared to rural dwellers.
- A follow-up study observed brain activities during stress tests, revealing that urban dwellers exhibited more stress reaction than rural counterparts.
- Both studies are observational; thus, conclusions about causation regarding city living and mental health cannot be definitively drawn.
Be Sure to Get Your Beauty Sleep!
- Research found that sleep affects perceived attractiveness; participants were rated post-sleep and after 31 hours of wakefulness.
- Conclusively, sleep-deprived individuals were rated less attractive.
- The study utilized a matched pairs design, allowing a causal relationship to be inferred between sleep quality and attractiveness perceptions.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge of categorical and quantitative variables with these MTHM 168 Chapter 1 flashcards. Each card presents a scenario for you to classify the variable type. Prepare to ace your understanding of data classification in statistics!
