LS15: Jay Phelan Midterm
How can you increase your experiment's power?
1) RANDOMIZE subjects across control and experimental groups 2) CONTROL your study 3) Use a DOUBLE BLIND design
Is eyewitness testimony infallible? Experiment
1) Stage a mock crime 2) present "suspects" to witnesses - 30% incorrect with standard lineup - 10% incorrect with sequential viewing Conclusions : standard line up is much less reliable But justice system often ignores this science because it makes it more complicated
What is Scientific Thinking?
1) We make observations 2) we formulate hypothesis 3) we make predictions based on the hypotheses 4) we devise and carry out experiments to test hypotheses and alternatives 5) we draw conclusions, modify hypotheses, and continue the process Allows you to change your mind if you're wrong
Types of Selection
1) directional 2) stabilizing 3) disruptive
Hyp. most useful when..
1) establish an explanation for the phenom 2) generate testable predictions
Darwin Common Themes in Nature
1) offspring overproduction a turtle couple leaves 30 eggs, so why is the world not overrun by all these turtles: numbers do not work!! 2) Competition for scarce resources giraffe fights 3) inheritance of traits offspring looks like parents
Charles Darwin
"I will confine myself to one special difficulty, which at first appeared to me insuperable, and actually fatal to the whole theory. I allude to the versatile females in insect communities... they cannot propagate their kind" "I can't figure out why there are sterile bees.." NEED TO FIGURE OUT THE ANNOYING COLLEAGUE
Dalai Lama 1997
"If scientific research proved certain Buddhism teachings to be incorrect, I would agree that the teachings should be changed accordingly."
1.16: Important themes unify and connect diverse topics in bio
"Life" is not easily described w a simple def, but rather is identified by the presence of certain characteristics shared by living orgs. 5 Themes of Bio : evolution, structure and function, info flow/exchange/storage, pathways/transformations of energy/matter, systems
Does it rain more on weekends?
- Collect past weather data and make a spread sheet showing day of the week and average rain fall - Data says it rains 22% more on Saturday than on Monday - HOW COULD THIS BE???? Particulate matter from car exhaust builds up all week when there is more driving This enhances cloud formulation and leads to rain Once it rains, the exhaust is washed away so no more rain - HOW COULD WE SEE THIS IS TRUE???? Last study done on east coast highway with a bunch of cars Now do it in the middle of nowhere in the ocean Found same amount of rainfall each week
Observation : a certain chemical may fight the AIDS virus Which experimental tests of this are better? Those done in a lab or those done in the real world? Why?
- Lab studies can be large and controlled, very certain - Real world studies very distracting, but it is realistic and shows it can actually be applied; much harder to control but you're trying to understand that scenario anyways
Cookie Experiment : Artificial vs. Real Vanilla
- Lady has no idea between the cookies - Still said she would use real vanilla, but then months later finally admits that it does not matter - Her mind was changed
Critical Experiment
- Putting a hypothesis to test - the results can decisively determine whether a hypothesis is correct - set it up to rule out h or not - For the cookie example, testing other desserts could cause you to change what you think
Beware of Anecdotes!
- We are overly biased by observations not based on careful study and/or not representative of the norm - Taking zinc when we are sick
What is evolution? (science)
- a change in allele frequencies in a population
Before Darwin
- all organisms were put on earth by a creator at the same time - orgs fixed: no additions, no subtractions - earth is about 6,000 years old - earth is mostly unchanging
Mean Genes Chapter 1
- brain is not an obedient servant - we must use passion and willpower to control our urges - Mean Genes Spectacles : see our world more accurately so we can control our instincts b4 they control us so we may live more satisfying lives w intergrity Thin wallets and Fat Bodies - ancestors used to eat all in front of them as hunter gatheres bc may have no food tomorrow that is why people spend so much too, money is a new concpet. we use these evo instincits
How does general scientific literacy - particularly among non scientists such as the volunteers in this study - help in advancing our knowledge and understanding ab a particular phenomenon?
- control group when testing the efficacy of an intervention is needed - unless we can demonstrate that the intervention leads to more desirable outcomes than no intervention, we should not make use of it - if subjects do not understand this, they may think it is unfair they may be in a control group w no intervention and may not want to do it - IN THE ABSENCE OF EVIDENCE FOR EFFICACY, WE CAN NOT ASSUME THAT AN INTERVENTION IS USEFUL
Less Sleep = More Likely to get sick Experiment What is a poor control here?
- diet, nutrition, genetics, gender, stress - should do it again and randomize the groups for peaceful sleeping and loud - keep them in hotel for 2 weeks and then expose to sickness
Charles Darwin Life Overview
- during his time, all species were placed on earth, never changed, never extinct - lazy teenager: "ordinary boy rather below common standard in intellect, "disgrace to yourself and family" - med school drop out - 1831-36: HMS Beagle trip around the world - Alfred Wallace almost scoops : collab but 1859 Darwin's Origin Of Species outshines Wallace
How long can a fly survive without food? Can we increase the average time to starvation in a population?
- fruit flies have smaller body mass, much shorter time than humans : around 20 hours until death - What if you only let the best flies reproduce?? Breed top 20% of starvation resistance - After 1 Gen: Average hours until death increases from 20 to 21 - 10 Gen: 28 hours - 60 Gen: 160 hours Fruit flies radically changed, even look different
Double Blind Design
- measurer should not know the experiment either so no biases or hints - If they want certain results, may not be as careful
People sometimes say that you can never definitively prove a hypothesis to be true, but that you can prove that a hyp is not true. How can this be? Is this a weakness of sci thinking? Why or why not? If we can't prove a hyp to be true, does that mean all hyps are equally likely to be true or not true?
- one piece of evidence that contradicts a hyp is sufficient for us to reject it and conclude alt hyp must be considered - impossible to prove a hyp is absolutely true bc there may be some future evidence of obs that proves it is not tue - usually speak of our increasing CONFIDENCE that a hyp is true as it withstands repeated tests in critical experiements - beauty of scientifc thinking : know when to change our minds
Darwin concluded that there is a STRUGGLE FOR EXISTENCE
- organisms better suited to an environment have a greater probability of surviving the struggle and will leave more offspring - through evolution, organisms may become better matched with their environment
After Darwin
- organisms change over time - some organisms have gone extinct - earth is more than 6,000 years old - geology of earth always changing
What is Scientific Thinking? General Explanation (more circular, not as linear as method)
- organized - empirical - methodical - structured way of finding info about observable events in nature (like seeing a movie in the theater vs at home, JMBD ratings!!) ENABLES US TO REJECT HYPOTHESES ABOUT HOW THE WORLD WORKS - way to learn and understand about anything (and you already use it; which is the best route to get to LAX?)
How does medical tech undo the work of NS?
- people who were supposed to die, do not anymore like babies in NIC unit - people who would have not been able to see predators before have contacts now!
Arnold Schwarzzenager Example
1) Make Observations: Arnold took steroids and is huge 2) Formulate Hypotheses (proposing explaination for observation): : "Taking steroids makes you muscular" *make sure testable and refutable 3) Make a prediction : if my hypothesis is true, when I do X, then Y will occur 4) Conduct an Experiment : Control all variables except one *need to take controls into account, think of everything! Eating habits, working out, randomized, double blind
H Vs Null H
H: echinacea reduces likelihood of catching the common cold and duration of symptoms NH: E has no effect on likelihood of catching or duration of symptoms
Scientific Thinking Example Study : Sleep and Attention Span (Step 1)
Observation : The less sleep I get, the less attention I pay in class
Is Maze Running ability in mice genetic? Experiment
Observation : some mice can learn the mazes very quickly H: some innate variation in understanding maze - Created smart and dumb mice : keep scores of mice then breed the top 20% w each other as well as the bottom 20% - "bright group" had less errors than "dull group"
Hypothesis
Proposed explanation for an observed phenomenon
Natural Selection
Darwin's Dangerous Idea A mechanism of Evolution 1) Variation 2) Heritable 3) Differential Reproductive Success
1.12: Visual displays of data can help us understand phenomena
Displays of data can aid in the presentation and exploration of the data. Their effectiveness is influenced by the precision and clarity of the presentation, and can be reduced by ambiguity, biases, hidden assumptions, and other issues that reduce a viewer's confidence in the underlying truth of the presented results *bar, line, pie
Scientific Thinking Example Study : Sleep and Attention Span (Step 5)
Draw conclusions, reconfigure hyp as needed: if there is a difference you can conclude the hypothesis is accurate sleep amount does affect attention span How much the person has been sleeping prior to them coming into the lab--- chronically sleep deprived people will have even lower amounts of attention span, regular short sleepers.
1.9: Is arthroscopic surgery for arthritis of the knee beneficial?
Evidence gained from well controlled studies designed in accordance with good scientific thinking can illuminate when we should change our minds. We make choices every day based on assumptions about our wold; it is essential to question these choices and the veracity of our assumptions
Scientific Thinking can tell you.... (THM)
When you should change your mind
Could we use the same experimental approach to change other pops?
Yes, but a little more difficult - on turkey farm, some turkeys are worth more money than others if they have large chests - would measure the turkeys and breed the best - average weight in turkey has increased significantly - now the turkeys are so big they can't even physically mate! In-vitro needed
biological literacy
ability to 1) use process of sci inquiry to think creatively about the real world issues tht have a biological component 2) communicate these thoughts 3) integrate these ideas into decisions
Pseudoscience and anecdotal observations can be..... (THM)
almost unbearably appealing, but should not influence our beliefs
1.15: There are limits to what science can do
although scientific thinking is an effective path toward understanding the observable world, it can't give us insights into value judgments and other nonquantifiable, subjective info
Scientific Thinking (observation, hypothesis, prediction, test, conclusion/revision) is... (THM)
an efficient pathway to understanding the world
Critical experiment
an experiment that makes it possible to decisively determine whether a particular hyp is better than the alt. EVIDENCE
placebo
an inactive substance used in controlled exp to test the effectiveness of another substance
science
an intellectual activity, encompassing methodical, objective observation; description; experimentation; and explanation of experimental phenomena pathway by which we can come to discover and understand our world
The better controlled an experiment is, the more confidence we should have in its results. But.... (THM)
as experiments are better controlled, they often are poorer models of the situation of interest
Anecdotal Observations
based on just one or a few obs, ppl conclude there is or is not a link between 2 things
Randomizing Subjects
better if ppl do not know what group they're in
biology
study of living things
Anecdotal Observations: autism is diagnosed right around the time children are vaccinated for measles, mumps, rubella
tempting to say vaccines cause autism.... FROM ANECDOTAL TO SCIENTIFIC -Testable predictions of the "vaccines cause autism" theory
If the 3 conditions are fulfilled.... (THM)
evolution by NS is occurring
Controlling an experiment
if we want to attribute a dif between 2 groups to the experimental treatment, there must be no underlying difs between the groups
Disruptive Selection
individual with extreme phenotypes experience highest fitness, and intermediate lowest # of fish v body size - good to be big bc you can fight for a woman, but small is unseen and will sneak in to reproduce - up down look
Directional Selection
individual with one extreme of the range of variation in population has higher fitness # of cows v milk production - breeding the best cows based on how much milk the cows produced - Milk production shifts either left or right - mini horses, dog breeding
Pseudoscience
individuals make scientific sounding claims that are not supported by trustworthy, methodical scientific studies
Stabilizing Selection
intermediate phenotypes most fit, eliminate extremes # of babies v birth weight - babies around 7 pounds have survival weight - 2 extremes go down, anything over or under 7 pounds has less chance of surviving - skinny look
empirical
knowledge based on experience and observations that are rational, testable, and repeatable
"One in Seven Fathers are not the real parent"
misleading because this is among the people who have a reason to get a paternity test
allele
one variant of a gene, several may exist Blue eyes
Scientific Method
rigid, linear, applied to narrow range of questions
In recent advertisements, the shoe company skechers made a variety of claims about a shoe they produced called "Shape-ups". The ads, some of which featured Kim K, include statements that the shoes provided more weight loss and muscle toning and strengthening of buttocks, legs, and abdominal muscles than regular fitness shoes. What evidence should Skechers be able to provide in order to make these assertions? Be specific ab exact ob they would need to make in order to demonstrate these claims as true.
Study between randomized sample of subjects of a broad demographic range : well controlled conditions of exercise, food intake, sleep, and prior conditioning Show that wearing shoes causes greater weight loss than those who wear regular shoes Show increases in muscle toning in said areas than those who wear regular shoes : should also give a definition of what "strengthening" means that fitness experts would agree with
1.1: Scientific thinking and biological literacy are essential in the modern world
Through its emphasis on objective observation, description, and experimentation, science is a pathway by which we can discover and better understand the world around us. And to make, smart decisions, biological literacy is essential.
1.4: Element 2 Formulate a hypothesis
A hypothesis is a proposed explanation for an observed phenomenon
1.10: We've got to watch out for biases
Biases can influence behavior, including our collection and interpretation of data. With careful controls, it is possible to reduce the impact of biases *when the sex of the first author was known by the reviewers, fewer papers by women were accepted for publication
Allele Differences
2 alleles can be the same (BB, bb) or different (Bb) Can measure the frequency of "B" and b"
Even slacker students in poor health... (THM)
Can change the world
Where do we get our genes from?
Carry 2 copies of every gene 1 from mom, one from dad
Scientific Thinking Example Study : Sleep and Attention Span (Step 4)
Conduct Experiment! Control : group of people getting 8 hours Experiment : sleep deprived Treatment : sleep vs no sleep Control other stress levels, eating, exercise, etc.
1.7: Element 5 - Draw conclusions, make revisions
EX: all groups were equally likely to develop a cold with symptoms lasting 3 days may need to now revise H and now better understand observable world w increasing activity
1.5: Element 3 - Devise a Testable Prediction
For H to be useful, it must generate a testable prediction EX: if E reduces the likelihood of catching the common cold and the duration of the symptoms of a cold then Ind who take it will have lower likelihood and shorter symptoms Ind who does not will have higher likelihood and longer symptoms
The evolution of starvation resistance
How long have you been without food? 24 hours; tired, lethargic, all you can think about is food 66 day hunger strike
The American Dental Association recs cleaning between teeth w dental floss once a day to reduce likelihood of suffering from gingivitis, the early stage of gum disease. In a recently published review of 12 published studies on the effects of flossing, however, researchers have questioned whether flossing has any value. What is the ADA's hyp? What are the associated predictions? Propose an experiment and analysis you would conduct and describe how it would test this assertion?
Hyp : Flossing each day will reduce the frequency and severity of gingivitis Prediction: individuals flossing each day will experience a lower frequency of ging than individuals not flossing Experiment: large group of individuals representative demographically and socioeconomically of the US. Randomly divided into groups One required to floss once a day, control instructed not to floss At regular intervals (twice a year) evaluate subjects and determine the frequency and severity of ging in the indv in each group Treatment = flossing vs not flossing similar diets, brush teeth twice a day with same brush, toothpaste, and for 1 minute Analysis : compare whether subjects who flossed daily have reduced frequency and severity of ging. Bc the only consistent and systematic dif between the 2 groups is whether or not they flossed, if flossing is beneficial, the flossing group will have reduced incidence and severity of ging. If no significant dif between cases in those who did and did not floss, flossing does not affect the likelihood of getting ging
Scientific Thinking Example Study : Sleep and Attention Span (Step 2)
Hypothesis: The hours of sleep a person gets affects their attention span the next day
What were the researcher's results? What conclusions can you draw from these results?
MEAN PAIN SCARE 1. Debridement : 51+-23 2. Lavage : 54+- 24 3. Placebo : or 52+- 24 The arthroscopic lavage surgery (with or without debridement) was not better than a placebo procedure in improving knee pain and self reported function
Scientific Thinking
Much more flexible for wide variety 1) make observations 2) formulate a hypothesis 3) devise a testable prediction 4) conduct a critical experiment 5) draw conclusions and make revisions
1.14 Pseudoscience and anecdotal evidence can obscure the truth
Often lead people to believe that links b/w 2 phenomena exist, when in fact there are no such links
10.2: Before Darwin, many believed that species had been created all at once and were unchanging
On a voyage around the world, Darwin noted unexpected patterns among fossils and living organisms. Fossils resembled but were not identical to living organisms in the same area. And finch species on each of the Galapagos Islands differed from one another in significant ways. These obs helped Darwin develop his theory of how species might change over time
Scientific Thinking Example Study : Sleep and Attention Span (Step 3)
Prediction: If sleep impacts attention span, then when people are sleep deprived, their attention span will be reduced compared to individuals that are not sleep deprived (or compared to themselves when they are not sleep-deprived).
How did the researchers decide whether the arthroscopic surgery was effective?
RANDOMLY ASSIGNED 1. Arthroscopic surgery with debridement : incisions in the knee joint and irrigation with fluid, followed by shaving, trimming, and smoothing the cartilage 2. Arthroscopic surgery with lavage : incisions in the knee joint and irrigation with fluid only. 3. Placebo Surgery : incisions in knee joint, followed only by manipulation of the knee as if arthroscopic surgery w debridement was being performed, with splashing of saline to stimulate lavage Patients spend night in hospital, cared for by nurses who did not know which group Evaluate effectiveness of the surgery at 7 points over the next 2 years ; would report knee pain and body pain and researchers measures of knee function (walking 100 ft and climbing up and down stairs ) 0-100 pain scale, Knee Specific Pain Scale
Humans have been making observations and formulating hypotheses about the nature of their world for a very long time. What additional element did the scientific method add that made it such a revolutionary advancement?
Sci Thinking adds TESTING OF THE PREDICTIONS specific to the hypothesis by a series of additional observations Predictions of hyp formulated and then additional obs made to confirm or invalidate hyp "The innovation of scientific thinking"
1.11: What are theories? When do hypotheses become theories?
Scientific theories do not represent casual guesses ab the natural world. Rather, they are hypotheses that have been so strongly and persuasively supported by empirical observation that the scientific community views them as very unlikely to be altered by new evidence
1.3: Element 1 - Make Observations
Scientific thinking begins by making obs about the world, nothing apparent patterns or cause and effect relationships EX; consuming extracts of the herb echinacea can reduce the likelihood of catching the common cold or shorten the duration of cold symptoms
1.2: Thinking like a scientist: how do you use the scientific method?
Scientific thinking is an empirical process that involves making observations, articulating hypotheses, generating predictions, designing experimental tests, and drawing conclusions. It is flexible adaptable, and efficient pathway to understanding the world, in part bc it tells us when we must change our beliefs
Beware of pesudoscience!
Scientific thinking is powerful but can be costly, time consuming, and difficult Cheating has appeal
1.13: Statistics can help us make decisions
Statistics can help us evaluate whether any difs between a treatment group and a control group can be attributed to treatment rather than chance
10.1: We can see evolution occurring right before our eyes
The characteristics of the individuals present in a population can change over time. We can observe such change in nature and cause it to occur
scientific literacy
a general, evidence based understanding of the basics of biology and other sciences
Week 0 Self Reflection : "I'm not a science person." Why might you (or someone you know) have ever said that? Using examples, explain a) why this is not actually an accurate assertion, and b) why this is potentially a harmful thing to say.
Throughout my senior year biology class, I told myself that I wasn't a science person. We spent a week dissecting rats and at the end of the week we were given a quiz. We were shown a part of the rat's insides on the smart board and then had to write the name of that organ or body part. As I sat there thinking about how every picture looked like the same exact pile of mush, my scientist ego was crushed. However, I did not realize that science comes in many different forms than the typical scientist in a lab coat image. I can now see the various places in my everyday life where I use scientific thinking. When my brother and I fight over which running path is more efficient and gets us more motivated to run, we are using our own past experiences and events to make our case. Although it may not sound like it, we have done trials in different running paths and have our own evidence for which running path is better. It can even be potentially harmful to say "I'm not a science person" because it puts science into a box. Science is ever changing and growing, which is why many discoveries are called theories. Scientists build off one another to get as close to the truth as possible. For example, without collaboration and open mindedness, society may have never moved from a geocentric model to the heliocentric model. If scientific ideas were boxed up, this growth and discovery could not be possible. Letting science have no borders gives everyone a new way to solve problems and find solutions, like my brother and I's running paths. In turn, saying that one is not a science person limits the possibilities of discovery in everyday life.
1.8: Controlling variables makes experiments more powerful
To draw clear conclusions from experiments, control and exp groups should differ only w respect to the treatment of interest. differences in outcomes between the groups can then be attributed to the treatment
1.6: Element 4 - Conduct a critical experiment
To test whether treatment prior to exposure influences the development or duration of symptoms, groups 1 (E) and 2 (P) receive tablets for 7 days prior to exposure while 3 and 4 do not Then after exposure 1 and 3 get E
Charles Darwin Years of Thinking : unexpected patterns observed
Unexpected Patterns 1) Finch Variation each island had unique species island species resembled mainland species maybe they used to be the same species??? 2) Similarity between fossils of extinct species and living species in an area extinct glyptodonts looked like giant armadillos
What is evolution? (general)
a gradual process in which something changes into a dif and usually more complex or better form - different pictures of the mustangs
population
a group of organisms of the same species living in the same geographic region
Species are not immutable....(THM)
We can watch them change in nature of even cause them to change
Many people believe that drinking eight glasses of water each day is beneficial for healthy people - prevents headaches, removes toxins, improves organ function, etc. In fact, numerous reviews of published clinical studies have found no scientific ev for this belief. Describe a behavior that suggests you have a particular belief ab actual world but do not know truth of it
Wearing lucky socks on game days Not eating carbs makes me feel less bloated
Pseudoscience: 9/10 doctors recommend brand X
What is wrong with this? - Lying and then trying to benefit from the strength/good of ST - How many doctors did they ask? How were they selected? What was the alternative? THEY WANT $$$$$ - Always be asking : how do you know what you claim to know?
Null Hypothesis
a h that states a lack of relationship between 2 factors
Persistent selection can... (THM)
dramatically change the morphology, behavior, and physiology of the individuals in a pop
Gene
section of DNA instructing how to produce a trait Eye color
