MTHM 168 Chapter 1 Flashcards

Questions and Answers

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.

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.

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?

Yes Signup and view all the answers

Which study provides better evidence that nut consumption reduces LDL cholesterol?

Study 1 Signup and view all the answers

Is the headline 'Antibiotics in infancy may cause obesity in adults' an appropriate conclusion based on the studies for mice and humans?

a) Yes, b) No Signup and view all the answers

In the study about green spaces making kids smarter, what are the cases?

The 2623 schoolchildren in Barcelona Signup and view all the answers

In the green spaces study, what is the explanatory variable?

Amount of greenery around school Signup and view all the answers

In the study about late-night eating, is the explanatory variable categorical or quantitative?

Categorical Signup and view all the answers

Can we conclude that eating late at night worsens some typical effects of sleep deprivation?

Yes Signup and view all the answers

In the study about beauty sleep, what is the response variable?

Attractiveness rating Signup and view all the answers

Is the study about beauty sleep an experiment or an observational study?

Matched pairs experiment Signup and view all the answers

Is the following variable categorical or quantitative? People in a city are asked if they support a new recycling law.

Categorical Signup and view all the answers

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.

Quantitative Signup and view all the answers

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?'

Categorical Signup and view all the answers

Is the following variable categorical or quantitative? Record whether or not the literacy rate is over 90% for each country in the world.

Categorical Signup and view all the answers

Number of years smoking cigarettes is the?

Explanatory Variable Signup and view all the answers

Yield of the crop is?

Response Variable Signup and view all the answers

BAC is the?

Response Variable Signup and view all the answers

Is the variable whether or not the spider engaged in mock sex categorical or quantitative?

Categorical Signup and view all the answers

Is the variable length of time for real mating categorical or quantitative?

Quantitative Signup and view all the answers

Is the variable length of time for real mating the explanatory variable or the response variable?

Response Variable Signup and view all the answers

Is estrogen concentration categorical or quantitative?

Quantitative Signup and view all the answers

Is fertility level categorical or quantitative?

Quantitative Signup and view all the answers

How many cases are there in the dataset of rowing times?

8 Signup and view all the answers

How many variables are there in this dataset of rowing times?

2 Signup and view all the answers

Is the type of diet variable categorical or quantitative?

Categorical Signup and view all the answers

Is metabolic status of the daughters variable categorical or quantitative?

Categorical Signup and view all the answers

Is metabolic status of the daughters the explanatory variable or the response variable?

Response Variable Signup and view all the answers

How many variables are mentioned in the elderly man's nose study description?

6 Signup and view all the answers

How many variables are categorical? How many are quantitative?

1 Categorical, 5 Quantitative Signup and view all the answers

How many cases and how many variables are in the hand-washing study?

47 Cases, 3 Variables Signup and view all the answers

Is the data for the trout recorded as a population or a sample?

Sample Signup and view all the answers

Is the data for the music website users a population or a sample?

Population Signup and view all the answers

Is the athletic participation questionnaire data a population or a sample?

Sample Signup and view all the answers

Does the sampling method used for drawing names from students produce a random sample?

Random Signup and view all the answers

Is the method described for selecting genes a random sample?

Random Signup and view all the answers

Does the sampling method for university students provide a random sample?

Not random Signup and view all the answers

Is the sampling method for CNN website visitors random?

Not random Signup and view all the answers

Is the method of data collection in the library poll biased?

Biased Signup and view all the answers

Is the method of data collection for bruises on apples biased?

Biased Signup and view all the answers

Is the method of data collection for printer performance biased?

Not biased Signup and view all the answers

Are the people who answered the work uniform poll likely to be representative of all adult workers?

No Signup and view all the answers

Is it reasonable to generalize that 24% of all adult workers would like to wear a uniform?

No Signup and view all the answers

Is the sample likely to be representative of all Canadian consumers?

Yes Signup and view all the answers

Is it reasonable to generalize this result to estimate that about 71% of all Canadian consumers regularly stream music?

Yes Signup and view all the answers

Is the sample likely to represent all registered voters in Iowa?

Yes Signup and view all the answers

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?

Yes Signup and view all the answers

What percent of people wash their hands after using the washroom based on observed behavior?

85% Signup and view all the answers

Why might there be a discrepancy in the percent from the telephone survey compared to the observed percent?

Self-reported behavior is often inaccurate and biased. Signup and view all the answers

Is the sample of 808 people likely to be representative of all US residents between ages 18 and 34?

Yes Signup and view all the answers

What population can we generalize from the findings of the NHANES study?

All people in the US Signup and view all the answers

What population can we generalize from the findings of the NHAMCS study?

All hospital emergency rooms in the US Signup and view all the answers

Which survey would probably address whether overweight people are more likely to develop diabetes?

NHANES Signup and view all the answers

Which survey would probably address the proportion of emergency room visits that involve sports-related injuries?

NHAMCS Signup and view all the answers

Which survey would probably address the difference in waiting time for male and female patients in the emergency room?

NHAMCS Signup and view all the answers

Which survey would probably address the proportion of US residents who have visited an emergency room within the past year?

NHANES Signup and view all the answers

Is the claim 'Daily exercise improves mental performance' one of association and causation or only association?

Association with causation Signup and view all the answers

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?

Neither association nor causation Signup and view all the answers

Is the claim 'Cell phone radiation leads to deaths in honey bees' one of association and causation or only association?

Association with causation Signup and view all the answers

Is the claim 'Cat owners tend to be more educated than dog owners' one of association only?

Association only Signup and view all the answers

Is the claim 'Want to lose weight? Eat more fiber!' one of association and causation?

Association with causation Signup and view all the answers

Is the study investigating if eating brown rice affects metabolism an experiment or an observational study?

Observational study Signup and view all the answers

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!