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Experimental and Observaational Studies

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Wize University Statistics Textbook > Experiments and Observational Studies

Experimental and Observational Studies

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Health is based on incidents of urinary tract infections (UTI), fleas, and tapeworms. Dr. Friskas provided this table:

TreatmentControl% Black cats32%28%% With spots or markings64%60%% Male52%44%% Experienced UTI12%36%% Had fleas16%44%% Had tapeworms8%20%\begin{array}{c|c|c} &\text{Treatment}&\text{Control}\\ \hline \text{\% Black cats}&32\%&28\%\\ \text{\% With spots or markings}&64\%&60\%\\ \text{\% Male}&52\%&44\%\\ \text{\% Experienced UTI}&12\%&36\%\\ \text{\% Had fleas}&16\%&44\%\\ \text{\% Had tapeworms}&8\%&20\% \end{array}

For example, 8% of cats that are fed a grain-free organic diet had tapeworms while 20% of cats that are not fed a grain-free, organic diet had tapeworms.

We can confidently say that a grain-free, organic diet is effective in reducing health problems for cats.
More Experimental and Observational Studies Questions:
Observational Studies
Which of the following is true about observational studies
(1) they can be used to make cause-and-effect conclusions about some variables of interest
(2) they can be used for statistical inference purposes
Experimental and Observational Studies
300 adults are divided according to their gender, and then divided again according to their age (20 or under, 21 to 30, 30 or above). Within each age group 5 to 10 members are randomly sampled and asked the question: what is your opinion about the latest generous government program for Universal Child Care?
This is an example of
Experimental and Observational Studies
A study is conducted to determine the effect a drug will have on patients' blood pressure. 80 adults are divided into two groups, male and female. Within each gender group, half of participants are randomly chosen to get the drug and the other half get the placebo. Those who are assigned the drug, will receive 1 microgram, 2 micrograms, or 3 micrograms, assigned randomly.
Experimental and Observational Studies
You are carrying out an experiment to test the effectiveness of 3 different dieting drugs. You divide up the 1000 participants in this study and randomly assign them one of the 3 drugs, then you randomly assign them one of the 2 different options for their drug. Which of the following statements is TRUE?
Experimental and Observational Studies
If we want to conclude the cause and effect of a certain drug with cancer, we must use a properly conducted
Experimental and Observational Studies
A study assigns each of the participants a different diet plan (the Keto Diet or Intermittent Fasting) as they sign up for the study. Three months later, it was found that the participants who were on the Keto Diet have lost 30% more weight compared to those who were assigned the Intermittent Fasting diet.
Which of the following statements are true? Select all that apply.
Experimental and Observational Studies
A farmer wants to see the effect on the size of tomatoes based on the type of fertilization (natural and synthetic) and amount of fertilization (none, some, and lots). Three hundred tomatoes seeds were randomly assigned to different types of fertilization and amounts.
Which of the following is true about this study?
Experimental and Observational Studies
A farmer wants to see the effect on the size of tomatoes based on the type of fertilization (natural and synthetic) and amount of fertilization (none, some, and lots). Three hundred tomatoes seeds were randomly assigned to different types of fertilization and amounts.
How many types of treatments are there in total?
Experimental and Observational Studies
A farmer wants to see the effect on the size of tomatoes based on the type of fertilization (natural and synthetic) and amount of fertilization (none, some, and lots). Three hundred tomatoes seeds were randomly assigned to different types of fertilization.
What is the explanatory variable? How many factors are there?
Experimental and Observational Studies
A farmer wants to see the effect on the size of tomatoes based on the type of fertilization (natural and synthetic) and amount of fertilization (none, some, and lots). Three hundred tomatoes seeds were randomly assigned to different types of fertilization and amounts.
What is the response variable?
Experimental and Observational Studies
A lab wants to test out a new drug called EYE-C for improving eyesight. They randomly sampled 100 subjects with poor eyesight and split them into two even groups. Each subject in Group 1 took the drug and each subject in Group 2 took a placebo. The subjects do not know which one they took; neither do the lab technicians. Results: 40 subjects in Group 1 reported improved eyesight, while 30 subjects in Group 2 reported improved eyesight.
Can you conclude that there is an association between the groups and improvement on eyesight?(YES/NO)
Experimental and Observational Studies
A lab wants to test out a new drug called EYE-C for improving eyesight. They randomly sampled 100 subjects with poor eyesight and split them into two even groups. Each subject in Group 1 took the drug and each subject in Group 2 took a placebo. The subjects do not know which one they took; neither do the lab technicians. Results: 40 subjects in Group 1 reported improved eyesight, while 30 subjects in Group 2 reported improved eyesight.
Which of the following is/are true/false?
a) This was an observational study.
Experimental and Observational Studies
Dr. Friskas want to determine if cats that are fed a grain-free, organic diet are healthier than cats that are not. She acquired 50 newborn kittens and randomly separated them into two groups. One group of kittens is fed a grain-free, organic diet; the other group is not. She monitored the cats’ health over time and noticed a sufficiently large difference in overall health between the two groups. She concluded that a cat’s diet significantly impact its overall health.
What is the treatment group?
Experimental and Observational Studies
Dr. Friskas want to determine if cats that are fed a grain-free, organic diet are healthier than cats that are not. She acquired 50 newborn kittens and randomly separated them into two groups. One group of kittens is fed a grain-free, organic diet; the other group is not. She monitored the cats’ health over time and noticed a sufficiently large difference in overall health between the two groups. She concluded that a cat’s diet significantly impact its overall health.
What is the control group?
Experimental and Observational Studies
Dr. Friskas want to determine if cats that are fed a grain-free, organic diet are healthier than cats that are not. She acquired 50 newborn kittens and randomly separated them into two groups. One group of kittens is fed a grain-free, organic diet; the other group is not. She monitored the cats’ health over time and noticed a sufficiently large difference in overall health between the two groups. She concluded that a cat’s diet significantly impact its overall health.
What is the response variable?
Experimental and Observational Studies
Dr. Friskas want to determine if cats that are fed a grain-free, organic diet are healthier than cats that are not. She acquired 50 newborn kittens and randomly separated them into two groups. One group of kittens is fed a grain-free, organic diet; the other group is not. She monitored the cats’ health over time and noticed a sufficiently large difference in overall health between the two groups. She concluded that a cat’s diet significantly impact its overall health.
What is the explanatory variable?
Experimental and Observational Studies
Dr. Friskas want to determine if cats that are fed a grain-free, organic diet are healthier than cats that are not. She acquired 50 newborn kittens and randomly separated them into two groups. One group of kittens is fed a grain-free, organic diet; the other group is not. She monitored the cats’ health over time and noticed a sufficiently large difference in overall health between the two groups. She concluded that a cat’s diet significantly impact its overall health.
Which of the following is most appropriate?
Experimental and Observational Studies
A farmer wants to see the effect on the size of tomatoes based on the type of fertilization (natural and synthetic) and amount of fertilization (none, some, and lots). Three hundred tomatoes seeds were randomly assigned to different types of fertilization and amounts.
How many types of treatments are there in total?