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Introduction to Experimental Science

Mrs. Donna Leonardi

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Scientists More than anything else, scientists are

skeptical. Most (not all) scientists do research to

gather data to prove or disprove hypotheses.

Scientists practice Discovery Science and/or Hypothesis Driven Science

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Research Methods

Researchers are . . .- like detectives – gather evidence,

develop a theory.- Like judges – decide if evidence meets

scientific standards.- Like juries – decide if evidence is

“beyond a reasonable doubt.”

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Science . . .

Is cumulative. Current research builds on previous research.

Usually Employs the Scientific Method: Empirical (acquires new knowledge via direct

observation and experimentation) Systematic, controlled observations. Unbiased, objective. Operational definitions. Valid, reliable, testable, critical, skeptical.

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What is Research?

Research is the scientists way of producing new information. Clearly defined steps Repeatable Clear and concise communication A search for a way to explain an observation

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Scientific Method

Making an observation, formulating a question, gathering background information, constructing a hypothesis.

Creation of the Research Investigational design, subjects, materials and procedures

Data Collection and Analysis Discussion and Interpretation of findings

and conclusion Next step action plan

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Observation

The pivotal event in research is the observationPublished materialPhysical eventTriggerThis event drives the entire focus

and direction of the investigationTake ownership of the investigation

which leads to more detailed observation

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Observation

An observation is the process of focusing on an object, organism, or event using one of more of your five senses, thought, or memory, for some unspecified amount of time and recording some aspect of that object or event.

The observation is stated objectively The observation does not include

interpretation

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Acid Rain

1959

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Make an Observation Activity 1

Write your name three times on a piece of paper with a pencil.

Tightly hold several ice cubes in your hand for one minute

At the end of one minute, immediately throw the cubes into a beaker and write your name three more times.

Warm your hands by rubbing them together.

Again write your name three more times. Make an observation and record it.

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Make an Observation Activity 2

Alex Rodriquez has hit 52 home runs this year and is a strong candidate for the American League MVP.

Alex Rodriquez is a right handed batter. Jorge Posada is also a candidate for American

League MVP. Jorge Posada is a switch hitter and has 19 home

runs. In the top 20 hitters in career batting average, there

are no switch-hitters. Two switch-hitters reside on the lists of most career base hits. In career home runs, Mickey Mantle is the top switch-hitter at No. 13. Mantle is the only switch-hitter in the top 20 in career home run percentage.

Make and observation and record it.

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Make an Observation Activity 3

The Erlenmeyer flask in front of you was filled with nutrient broth and subsequently autoclaved.

The flask was placed into the refrigerator over the summer.

The organism growing in the flask appears to be bread mold, Rhizopus stolonifer .

There appears to be a centrally located focus in the spherical formations of mold in the flask.

To the best of my knowledge, the flask was never opened after being autoclaved.

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Objective Observation

Stated in the form of a declarative sentence

Stated in a clear and detailed manner, limiting it to a single element or event as much as possible

The sensory experiences should be recorded or documented as accurately as possible with no interpretation

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Objective Observation

Pure reflection of what is experienced Taste (gustatory) Auditory Olfactory Touch (Haptic) Visual Does not include any feelings or

thoughts about what you sensed

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Subjective Observation Avoid subjective observations

Interpretations thoughts and feelings about what you experienced through your senses.

Subjective or objective???? Electrical impulses coming from the electric eel

speed up when the lights are turned off. Electric impulses coming from the electric eel

speed up greatly when the lights are turned off.

Rewrite you observation from the ice cube experiment or the batting observation.

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Background Information Activity 2

In baseball, a switch-hitter is a batter who is able to hit from both the right and left sides of the plate.

Right-handed batters have a higher batting average against left-handed pitchers and vice-versa

Players learn to switch-hit. Reaction time (RT) is the elapsed time between

the presentation of a sensory stimulus and the subsequent behavioral response.

http://biae.clemson.edu/bpc/bp/Lab/110/reaction.htm

Continued…..

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J Am Optom Assoc. 1997 Jan;68(1):43-9.

Association between visual reaction time and batting, fielding, and earned run averages among players of the Southern Baseball League.

Classé JG, Semes LP, Daum KM, Nowakowski R, Alexander LJ, Wisniewski J, Beisel JA, Mann K, Rutstein R, Smith M, Bartolucci A.

School of Optometry, University of Alabama at Birmingham 35294, USA. BACKGROUND: This study was performed to investigate the relationship between

vision reaction time (VRT) and batting, fielding, and pitching skill in baseball. METHODS: A vision screening of 213 professional baseball players in the Southern Baseball League was performed, and the visual reaction times of these players were determined. Official Southern Baseball League statistics were consulted to obtain the players' batting average, fielding average, and earned run average. RESULTS: The mean visual reaction time for all players was 239 msec. There was no significant association between mean VRT and age or race. The mean VRT for dominant eyes was not significantly different from the mean VRT for nondominant eyes. For the 92 players who batted at least 100 times, an association was found between mean VRT and batting average (p = 0.017). For the 168 fielders in the league playing at least 20 games, no statistically significant association was found between mean VRT and fielding average. Similarly, no association was found between mean VRT and earned run average for the B8 pitchers who had participated in more than 20 games. CONCLUSIONS: An association was found between visual reaction time and batting skill in baseball. No association was found between visual reaction time and fielding or pitching skill.

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A hypothesis to explain the observation From Activity 2

There is a statistically significant difference between reaction time when a switch hitter bats from the right or the left side of the plate.

There is a statistically significant difference between the reaction time of the right and left hand.

Your Hypotheses

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The Experiment for Activity 2

Reaction Time Calculation

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The Experimental Plan We have made a pivotal observation that switch hitters hit

fewer homeruns than non switch hitters. Background research has led me to the idea that reaction

time affects batting success (J Am Optom Assoc. 1997 Jan;68(1):43-9).

Background research has also led me to the idea that reaction time may differ between the right and left hand, and that this is the reason switch hitters hit statistically fewer homeruns and have a lower batting average than non switch hitters.

In my background research, I have never checked to see if switch hitters have developed faster reaction times than the general population with their non dominant hand, if, indeed, there is a difference in reaction time between the dominant and non dominant hands. .

In my background research, I have never checked to see that right handed switch hitters hit more homeruns when they are batting right handed.

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1. The first step in planning an experiment is choosing an answerable question.

Progress in an area is made by rejecting a hypothesis. This is the logical experimental framework.

There is no such thing as PROOF. All the possible alternative explanations for

a phenomenon or all experimental outcomes must be listed and an attempt made to eliminate each possibility.

The most likely explanation to me is that there is a difference in reaction time between dominant and non dominant hands.

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2. The second step in an experimental design is determining what kind of data will be needed to answer your question.

What kind of data? How much data? Determine appropriate

sample size. The entire experiment should be thought

through at the start!! All the statistical tests are merely ways to

examine different kinds of data, collected in different ways, to determine whether you have a statistically significant reason to reject your Null Hypothesis.

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The Null Hypothesis

Because the logical experimental framework is based on the rejection of hypotheses, experiments usually begin with the Null Hypothesis.

The Null Hypothesis is the hypothesis of no difference.

What is the Null Hypothesis in our case?

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The Null Hypothesis Ho

Ho There is no difference between the reaction time of the dominant and non dominant hand.

If I fail to reject the Null Hypothesis with no significant findings, my experiment is over.

If I fail to reject the Null Hypothesis and have significant findings, this is an important step forward.

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The Alternative Hypothesis Ha

Since I am interested in showing there is a difference, my Alternative hypothesis would read: There is a difference between the

reaction time of the dominant and non dominant hand.

I have stated nothing about which hand would have a faster reaction time.

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Alternative Answers must be listed within the logical framework

H1 = Reaction time in the dominant hand is faster than reaction time in the non dominant hand.

H2 = Reaction time in the non dominant hand is faster than reaction time in the dominant hand.

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A research proposal must be written at this time

Question being asked Statement of the Null and Alternative Hypotheses Justification of the effort (Why? What is the big picture?

Relevant published literature mentioned.) and expense Experimental design including specific equipment and

techniques (Reference to previously published procedures being followed.

Controls and variables described Sample size Flow chart of decision points in the experiment (If A

then B). Statistical method being employed.

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Basic Research Proposal Format

Title Question Why This Question Experimental Logic Ho, H1, H2 etc. Methods and Materials Proposed Statistical Treatment

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Let’s get started!!

Ho There is no difference between the reaction time of the dominant and non dominant hand

H1 = Reaction time in the dominant hand is faster than reaction time in the non dominant hand.

H2 = Reaction time in the non dominant hand is faster than reaction time in the dominant hand

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Data Collection

Collecting reaction time data Reaction time t = √(2d/g) How many pieces of data?

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What Statistical Method?

Using the resources provided, determine which statistical method is most appropriate for the data?