fsn 1500 week 1 the scientific method and dimensional analysis

FSN 1500 Week 1

The Scientific Method and Dimensional Analysis

Foreword

The average person may feel overwhelmed by the amount of scientific information and applications being produced and their ability to understand its consequences

Examples: Does global climate change really affect me? Will a prescription medicine help, or harm me? Is my water safe to drink? What type of diet is the healthiest?

We all need to be more informed consumers of scientific information so we can make beneficial decisions

Foreword

Science – a method of acquiring knowledge through use of the “scientific method”

The scientific method is the hallmark of a correctly conducted scientific study

Don’t always assume that studies reported in the lay press have been conducted properly or the results interpreted correctly; a well-done study should generate results that are reproducible by other researchers

Concerns

This statement is critical; a 2005 study, published in the Journal of the American Medical Association, reviewed whether the initial results of a single study were validated for more than 45 major medical studies published in leading journals from 1990-2003

Subsequent research contradicted 16% of the initial studies and reported weaker conclusions for another 16% (nearly a third of the initial studies results weren’t validated

A more recent article suggests even more difficulty in replicating initial study results in pharmaceutical research (see slide)

Source: Wall Street Journal 12/2/2011

Therefore: be a careful consumer of scientific information (especially medical) – the more studies which reach the same conclusions the more confidence you can have in those conclusions

Concerns

Remember; good scientific research is highly reproducible!

As we’ll continue to stress, science has limitations when it comes to studying human health and behavior.

Concerns

In addition, don’t always assume that the lay press reporters, especially in local markets, have a sufficient science background to correctly report research results or properly explain science topics (e.g., my summer 2007 experience with a television station reporting about an “ozone action day”) Los Angeles, CA

Scientific Method

The Scientific Method can be subdivided into four steps.

1) Collect information relevant to the study problem via observation and/or experimentation (e.g., What’s the best inflation speed for vehicle airbags?). Analyze data to discern relationships (trends) pertinent to the problem.

Scientific Method

2) Formulate an hypothesis* (preliminary explanation) to explain the data relationships that can be tested (judged) by further observations or experiments.

* can precede step 1

Scientific Method

3) Plan and do additional tests (experiments and/or observations) of the hypothesis. Analyze the new data.

4) Modify the original hypothesis, if necessary, to be compatible with the new information, or discard the original hypothesis. (See figure.)

Related Terms

Hypothesis – tentative (preliminary), testable explanation or working model

Theory - an hypothesis that’s well supported by the accumulated data; an explanation or model with considerable supporting evidence

Scientific Law – a simple statement of natural phenomena to which no exceptions are known under the given conditions; famous example?

Related terms

Pure (Basic) Science - study that increases the general body of knowledge but for which the investigators have no forethought application (e.g., early experiments with radioactivity)

Applied Science (Research and Development) - study conducted with a specific application in mind (e.g., What is the best inflation speed for vehicle airbags?)

Important Considerations

1) New evidence may necessitate revision or rejection of older theories (e.g., cause of nearly all ulcers).

The early 1980s work of Drs. Barry Marshall and Robin Warren supporting the connection between Helicobacter pylori infections and most ulcers was strongly resisted by the medical orthodoxy until the mid 1990s

Marshall and Warren were awarded the Nobel Prize for medicine in 2005


• 2) Science is not static (unchanging) but dynamic (constantly evolving).

• 3) A theory can’t be proven with 100% conclusiveness; science disproves possibilities but can’t with no uncertainty prove a possibility. (Think about scientific political polling results.)


• Another way of phrasing the previous idea: a scientific idea is one that makes predictions that can be proven false


4) Correlation does not guarantee causation; public must differentiate between a “link”(an association) and a cause-and-effect relationship; especially when considering human health studies.

Examples?

Science Link Examples

1) Living in proximity to high-voltage power lines and higher incidence of childhood leukemia (see slide)

2) Media (television, cinema, video games, music) violence exposure and rates of societal violence

3) Cellular phone usage and higher rates of brain tumors (see attached article and slide)

4) Cellular phone use and short-term memory loss 5) Gambling and higher suicide rates in cities hosting casinos 6) Others?

6/3/05


1) Living in proximity to high-voltage power lines and higher incidence of childhood leukemia


3) Cellular phone usage and higher rates of brain tumors (see slides)


10/14/04


International Business News

Oakland Press,12/6/06


Oakland Press 12/6/06

5/31/2011


1) Living in proximity to high-voltage power lines and higher incidence of childhood leukemia


3) Cellular phone usage and higher rates of brain tumors (see attached article and slide)



Remember: especially with issues involving humans (e.g., the effects of food pesticide residues on human health), it may be very difficult to pinpoint with high certainty a cause-and-effect relationship since:

1) it may be difficult to understand the effects of “confounding factors” (e.g., lifestyle, diet, heredity); even clinical trials have this limitation

2) controlled testing of the human population may be impossible or is unethical, especially if the study could produce negative health results

Therefore “science” has limitations when attempting to understand human health and actions

Good Scientist Qualities

Is a dispassionate, objective observer that begins a study with no preconceived notions (e.g., older students value their educational opportunity more than recent high school graduates)

Develops multiple hypotheses initially and allows the study data to eliminate those hypotheses that don’t agree with the data

Strives to eliminate bias, both unintentional (e.g., incorrect sampling technique) and intentional (e.g., specifically excluding or falsifying some data; misrepresenting study results) from any study

Bad Science Practices

One of the most famous examples of unintentional bias involved the projection of political polling by the Literary Digest to the 1936 presidential election.

This magazine conducted a “straw poll”, with 2.4 million people responding from their readership and mailings sent to owners of automobiles and home telephones

Candidates? Their prediction? Election results? Problem with their approach?


Perhaps more disturbing is the potential for intentional bias in scientific research (see slides)

Wall Street Journal June 9, 2005

11/29/2006

Bloomberg.com; 2/27/09


CNN.com; 1/6/2011

Update


• “Confirmation Bias” can be intentional or unintentional (e.g., subconscious)

• Essentially ignores or excludes data/information that discredits or challenges previous conclusions/beliefs

• Sometimes it is said that “we hear what we want to hear and see what we want to see”

Discover: January 2004


Should the previous slides give you cause for concern? Yes!

Can you think of any relatively recent examples illustrating why?

TUESDAY, July 13 (HealthDay News) -- The pharmacy company that makes Avandia knew more than a decade ago that the blockbuster diabetes drug caused an increased risk of heart problems but covered up the information, according to a report published Tuesday in The New York Times.In a 1999 trial pitting Avandia against its competitor, Actos, the drug company, then known as SmithKline Beecham, found that Avandia posed a heart risk, the newspaper reported.

Business Week 7/13/2010

DiscoverMagazine’sFifth MostImportant Science StoryOf 2007

Update

In late 2013 a few U.S. researchers established the Center for Open Science

This initiative has created a Web portal where scientists can easily log their data, methods and results to make it easier for other scientists to try to replicate their work

The Center also provides grants to researchers to encourage the replication of key studies

Bad Science PracticesNew York Times

Advice to the Layperson

• Therefore, always consider the credibility and integrity of your information sources, including scientific information

• Perhaps it is also wise to consider the following phrase when evaluating media information (including scientific) – “Follow the ________.”

Good Scientist Qualities

Records all data, clearly documents calculations, expresses conclusions in a legible, verifiable fashion; “good” science must be reproducible

Remember: with the likely exception of scientific laws, all scientific ideas are temporary and will eventually be modified or replaced

Science Today

Is becoming increasingly interdisciplinary (e.g., risk assessment, Earth system science)

Still sometimes produces serendipitous (accidentally fortunate) results (e.g., William Buehler, Frederick Wang and the discovery of nitinol) (view demonstration)

Science Today

Uses of “memory metal”? Suggestions? Then view the next slide.

Memory Metal Uses

Examples: braces, vascular stents (see photos)

Others: anti-scald water cutoff valves, coffee pot thermostats, bendable surgical tools, eyeglass frames, anchors for attaching tendons to bone, underwire brassieres!

Other serendipitous scientific discoveries range from penicillin to Post-It notes!

Serendipity in Science

Nearly 50 years after its accidental discovery, scientists are still trying to develop different types of memory metals

Serendipity in Science

Pay attention to the news for more serendipitous science

The Metric System and Dimensional Analysis

Only three countries, the U.S., Liberia and Myanmar don’t use the Metric System as their standard system of measure - even though the U.S. Congress officially adopted it as our standard in 1893!

The metric system is defined by base units whose multiples are indicated by a special prefix; the base units vary by powers of ten


E.G., meter (base unit); millimeter (0.001 meter); kilometer (1000 meters)

Let’s quickly look at one of our handouts - don’t worry about memorizing these measurement units - know how to find the units and their English system equivalents


Be able to use dimensional analysis to routinely convert measurement units and values (English Metric, Metric English)

Dimensional Analysis

Dimensional Analysis: method of measurement unit accounting and conversion; dimension - a measure of spatial, time or energy extent

Basis: starting unit x conversion factor(s) = desired unit

Conversion factor (equivalence expression) expresses relationship between the starting and desired units; e.g., 1 inch (in) = 2.54 centimeters (cm)


Written as: 1 in/2.54 cm or 2.54 cm/1 in (conversion factors)

Read as: 1 in = 2.54 cm; 2.54 cm = 1 in (equivalence expressions)

See “Rules” section of handout for the rules of dimensional analysis (following figure)

Rules:


E.G., 11 in = ? cm 11 in x 2.54 cm/1 in = 28 cm or 11 in x 1 cm/0.3937 in = 28 cm See the following figure for more examples;

no need to memorize conversion factors; use the provided sheet of conversion factors or an appropriate table


Board example: consider a large rectangular raised flower bed for which you wish to purchase topsoil. The bed has dimensions of 45 feet long and 25 feet wide. You wish the topsoil to be applied to a uniform depth of 6 inches.

If the topsoil costs $22 per cubic yard*(delivery included), can you afford to purchase the topsoil you need with the $500 you’ve saved for this project?

* $22 per cubic yard = $22/yd3


Please practice until you can perform this technique with ease; good science is clearly recorded and verifiable - the correct answer without a clear, verifiable calculation record is not very valuable

Follow “stress-free” approach outlined in handout (see following figure)

Assignment Instructions

Measure the length and width of the assignment sheet in inches and centimeters with the provided rulers – complete the requested conversions at home.

Gather the data, volume and mass, to calculate the density of the supplied wooden block and water – complete the calculations at home.

Complete the remaining word problems at home. You must use the dimensional analysis technique.

fsn 1500 week 1 the scientific method and dimensional analysis

Documents

slide slide

scientific method

ca slide

scientific study dont

good scientific research

initial study results

dimensional analysis

beneficial decisions