study of living organisms
biology
a systematic method of research consisting of putting a hypothesis to a test designed to disprove it, or not.
scientific method
a proposed explanation for one or more observations
• Testable and falsifiable
ex: Consuming Vitamin C reduces the risk of catching a cold
• Testable and falsifiable
ex: Consuming Vitamin C reduces the risk of catching a cold
hypotheses
Science is a process of testing hypotheses- statements about how the natural world works. Scientific hypothesis must be testable and falsifiable
Describe the characteristics of a scientific hypothesis.
A scientific theory is an explanation of a set of related observations based on well-supported hypotheses from several different, independent lines of research
Compare and contrast the terms “scientific hypothesis” and “scientific theory”
-Hypotheses are often developed via inductive reasoning, which consists of making a number of observations and then inferring a general principle to explain them
-Hypotheses are tested via the process of deductive reasoning, which allows researchers to make specific predictions about expected observations
-Hypotheses are tested via the process of deductive reasoning, which allows researchers to make specific predictions about expected observations
Distinguish between inductive and deductive reasoning.
Absolutely proving hypotheses is impossible because there may be other reasons besides the one hypothesized that could lead to the predicted result
Explain why the truth of a hypothesis cannot be proven conclusively via deductive reasoning.
possible to evaluate through observations of the measurable universe
testable
proven false
falsifiable
explanation for a set of related observations that is based on well-supported hypotheses from different, independent lines of research.
• Process used to construct a hypotheses→ inductive reasoning
• Process used to construct a hypotheses→ inductive reasoning
scientific theory
combining a series of observations to discern a general principle
inductive reasoning
making a prediction about the outcome of a test
“if…then” statements
-allows researchers to make specific predictions about expected observations
“if…then” statements
-allows researchers to make specific predictions about expected observations
deductive reasoning
result of what we expect from a hypothesis test
prediction
1. hypothesis- Consuming vitamin C reduces the risk of catching a cold (testable and falsifiable)
2. make a prediction- If Vitamin C decreases the risk of catching a cold, then people who take vitamin C supplements will experience fewer colds than people who do not.
3. test prediction- Conduct experiment or suvery to compare number of colds in people who do and do not take vitamin C supplements
4. conclusion: reject or accept. Conclude that hypothesis is either true or false
5. do not reject- conduct additional tests. reject- consider alternative hypothesis
2. make a prediction- If Vitamin C decreases the risk of catching a cold, then people who take vitamin C supplements will experience fewer colds than people who do not.
3. test prediction- Conduct experiment or suvery to compare number of colds in people who do and do not take vitamin C supplements
4. conclusion: reject or accept. Conclude that hypothesis is either true or false
5. do not reject- conduct additional tests. reject- consider alternative hypothesis
scientific method
hypothesis: Consuming vitamin C reduces the risk of catching a cold (testable and falsifiable)
step 1 of scientific method
make a prediction- If Vitamin C decreases the risk of catching a cold, then people who take vitamin C supplements will experience fewer colds than people who do not.
step 2 of scientific method
test prediction- Conduct experiment or suvery to compare number of colds in people who do and do not take vitamin C supplements
step 3 of scientific method
conclusion: reject or accept. Conclude that hypothesis is either true or false
step 4 of scientific method
do not reject hypothesis- conduct additional tests. reject hypothesis- consider alternative hypothesis
step 5 of scientific method
factor other than the tested hypothesis that may explain observations.
alternative hypothesis
defined as “what we know and understand based on currently available information”
“truth”
set of actions or observations designed to test specific hypotheses.
experiments
information collected by scientists during hypothesis testing
data
factor that varies in a population over time
variable
manipulated, influences dependent
independent variable
“depends” on independent, what is being measured in the experiment
dependent variable
-Controlled experiments test hypotheses about the effect of experimental treatments by comparing a randomly assigned experimental group with a control group
-controls are individuals who are treated identically to the experimental group EXCEPT for application of the treatment
-controls are individuals who are treated identically to the experimental group EXCEPT for application of the treatment
Describe the features of a controlled experiment, and explain how these experiments eliminate alternative hypotheses for the results
bias in scientific results can be minimized with double-blind experiments that keep subjects and data collectors unaware of which individuals belong in the control or experimental group
• Nearly eliminates human bias
• Results are more credible
• Double-blind, placebo-controlled, randomized experiments= ideal
• Difficult to perform when humans are the subjects
• Placebo treatment are unethical in some cases
o Ex: effectiveness of birth control
• Nearly eliminates human bias
• Results are more credible
• Double-blind, placebo-controlled, randomized experiments= ideal
• Difficult to perform when humans are the subjects
• Placebo treatment are unethical in some cases
o Ex: effectiveness of birth control
strategies for minimizing bias when designing experiments
If performing controlled experiments on humans is considered unethical, scientists sometimes use this
-the correlation of structure and function between humans and model organisms, such as other mammals, allows experimental tests of these hypotheses
-correlation DOES NOT = causation; correlations cannot exclude alternative hypotheses. Thus, a correlation study can describe a relationship between two factors, but it does not strongly imply that one factors causes the other
-the correlation of structure and function between humans and model organisms, such as other mammals, allows experimental tests of these hypotheses
-correlation DOES NOT = causation; correlations cannot exclude alternative hypotheses. Thus, a correlation study can describe a relationship between two factors, but it does not strongly imply that one factors causes the other
correlation
-these tests help scientists evaluate the result of their experiments by determining if results appear to reflect the true effect of an experimental treatment on a sample of a population
-____ significant result is one that is very unlikely to be due to chance differences between the experimental and control group
– even when an experimental result is highly significant, hypotheses are tested multiple times before scientists come to a consensus on the true effect of a treatment
-____ significant result is one that is very unlikely to be due to chance differences between the experimental and control group
– even when an experimental result is highly significant, hypotheses are tested multiple times before scientists come to a consensus on the true effect of a treatment
statistical test
subject for an experiment who is similar to experimental subject except is not exposed the experimental treatment
• Designed to eliminate as many alternative hypotheses as possible
• Experimental vs. control group= differences in the result may be due to the experimental treatment
• Designed to eliminate as many alternative hypotheses as possible
• Experimental vs. control group= differences in the result may be due to the experimental treatment
control group
Effective way to minimize differences between groups; placing individuals into experimental and control groups randomly to eliminate systematic differences between the groups
• Treat all participants the same ensures that no factor related to the interaction btwn subject and researched influences the results.
• Treat all participants the same ensures that no factor related to the interaction btwn subject and researched influences the results.
Random Assignment
sham treatments in experiments
experimental results caused by expectations alone
experimental results caused by expectations alone
placebo effect
experimental results published in professional journals and peer-reviewed by other scientists before publication
primary sources
typically news, books, or websites that summarize the scientific research presented in primary sources. They are NOT peer-reviewed and sometimes contain poorly supported information
secondary sources
-anecdotal evidence is an unreliable means of evalutating information, and media sources are of variable quality; distinguishing between news stories and advertisements is important when evaluating the reliability of information. The internet is a rich source of information, but users should look for clues to a particular website’s credibility
-stories about science should be carefully evaluated for information on the actual study performed, the universality on the claims made by the researchers, and other studies on the same subject. Sometimes confusing stories about scientific information are a reflection of controversy within the scientific field
-stories about science should be carefully evaluated for information on the actual study performed, the universality on the claims made by the researchers, and other studies on the same subject. Sometimes confusing stories about scientific information are a reflection of controversy within the scientific field
Summarize the techniques you can use to evaluate scientific information from secondary sources
expecting a particular outcome might lead scientist to give slightly different instructions
observer bias
A placebo allows members of the control group to be treated exactly like the member of the experimental group EXCEPT for their exposure to the independent variable
What is the value of the placebo effect?
B- My cow eats grass and my neighbor’s cow eats grass; therefore, all cows eat grass
Which of the following is an example of inductive reasoning?
A. All cows ear grass
B. My cow eats grass and my neighbor’s cow eats grass; therefore, all cows eat grass
C. If all cows eat grass, when I examine a random sample of all the cows in Minnesota, I will find that all of then eat grass
D. Cows may or may not eat grass, depending on the type of farm where they live
A. All cows ear grass
B. My cow eats grass and my neighbor’s cow eats grass; therefore, all cows eat grass
C. If all cows eat grass, when I examine a random sample of all the cows in Minnesota, I will find that all of then eat grass
D. Cows may or may not eat grass, depending on the type of farm where they live
B- a proposed explanation for an observation
A scientific hypothesis is…
A. an opinion
B. a proposed explanation for an observation
C. a fact
D. easily proved true
E. an idea proposed by a scientist
A. an opinion
B. a proposed explanation for an observation
C. a fact
D. easily proved true
E. an idea proposed by a scientist
D- It can explain a large number of observations
How is a scientific theory different from a scientific hypothesis?
A. It is based on weaker evidence
B. It has not been proved true
C. It is not falsifiable
D. It can explain a large number of observations
E. It must be proposed by a professional scientist
A. It is based on weaker evidence
B. It has not been proved true
C. It is not falsifiable
D. It can explain a large number of observations
E. It must be proposed by a professional scientist
A- eople who eat chicken noodle soup have shorter colds than people who do not eat chicken noodle soup
One hypothesis states that eating chicken noodle soup is an effective treatment for cold. Which of the following results does this hypothesis predict?
A. People who eat chicken noodle soup have shorter colds than people who do not eat chicken noodle soup
B. People who do not eat chicken noodle soup experience unusually long and severe colds
C. Cold viruses cannot live in chicken noodle soup
D. People who eat chicken noodle soup feel healthier than do people who do not eat chicken noodle soup
E. Consuming chicken noodle soup causes people to sneeze
A. People who eat chicken noodle soup have shorter colds than people who do not eat chicken noodle soup
B. People who do not eat chicken noodle soup experience unusually long and severe colds
C. Cold viruses cannot live in chicken noodle soup
D. People who eat chicken noodle soup feel healthier than do people who do not eat chicken noodle soup
E. Consuming chicken noodle soup causes people to sneeze
D- B and C are correct
If I perform a hypothesis test in which I demonstrate that the prediction I made in question 5 is true, I have
A. proved the hypothesis
B. supported the hypothesis
C. not falsified the hypothesis
D. B and C are correct
E. A, B and C are correct
A. proved the hypothesis
B. supported the hypothesis
C. not falsified the hypothesis
D. B and C are correct
E. A, B and C are correct
E- all of the above
Control subjects in an experiment…
A. should be similar in most ways to the experimental subjects
B. should not know whether they are in the control or experimental groups
C. Should have essentially the same interactions with the researchers as the experimental subjects
D. help eliminate alternative hypotheses that could explain experimental results
E. all of the above
A. should be similar in most ways to the experimental subjects
B. should not know whether they are in the control or experimental groups
C. Should have essentially the same interactions with the researchers as the experimental subjects
D. help eliminate alternative hypotheses that could explain experimental results
E. all of the above
C- double-blind
An experiment in which neither the participants in the experiment nor the technicians collecting the data know which individuals are in the experimental group and which ones are in the control group is known as..
A. controlled
B. biased
C. double-blind
D. falsifiable
E. unpredictable
A. controlled
B. biased
C. double-blind
D. falsifiable
E. unpredictable
B- correlation
A relationship between two factors, for instance, between outside temperature and the number of people with active colds in a population is known as
A. significant result
B. correlation
C. hypothesis
D. alternative hypothesis
E. experimental test
A. significant result
B. correlation
C. hypothesis
D. alternative hypothesis
E. experimental test
C- articles in peer-reviewed journals
A primary source of scientific results is
A. the news media
B. anecdotes from others
C. articles in peer-reviewed journals
D. the internet
E. all of the above
A. the news media
B. anecdotes from others
C. articles in peer-reviewed journals
D. the internet
E. all of the above
B -The difference between chocolate and non-chocolate eating rats in heart disease rates was greater than expected by chance
A story on your local news station reports that eating g a 1-ounce square of milk chocolate each day reduces the risk of heart disease in rats, and that this result is statistically significant. This mean that…
A. People who eat milk chocolate are healthier than those who do not
B. The difference between chocolate and non-chocolate eating rats in heart disease rates was greater than expected by chance
C. Rats like milk chocolate
D. Milk chocolate reduces the risk of heart disease
E. Two ounces of milk chocolate per day is likely to be even better for heart health than 1 ounce
A. People who eat milk chocolate are healthier than those who do not
B. The difference between chocolate and non-chocolate eating rats in heart disease rates was greater than expected by chance
C. Rats like milk chocolate
D. Milk chocolate reduces the risk of heart disease
E. Two ounces of milk chocolate per day is likely to be even better for heart health than 1 ounce
E- all of the above
What features of the story on milk chocolate and heart health described in question 11 should cause you to consider the result less convincing?
A. the study was sponsored by a large milk chocolate manufacturer
B. A total of 10 rats were used in the study
C. The only difference between the rats was that subjects of the experimental group received chocolate along with their regular diets, while subjects of the control group received no additional food
D. The reporter notes that other studies indicate milk chocolate does not have a beneficial effect on heart health
E.all of the above
A. the study was sponsored by a large milk chocolate manufacturer
B. A total of 10 rats were used in the study
C. The only difference between the rats was that subjects of the experimental group received chocolate along with their regular diets, while subjects of the control group received no additional food
D. The reporter notes that other studies indicate milk chocolate does not have a beneficial effect on heart health
E.all of the above
