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The Nature of Science & Science Skills Test Review Research starts with a … Research question What the scientists wants to know What are the two general types of research: Experimental Descriptive Descriptive research is… Based mainly on observations
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The Nature of Science & Science Skills Test Review
Research starts with a … • Research question • What the scientists wants to know
What are the two general types of research: • Experimental • Descriptive
Descriptive research is… • Based mainly on observations
Examples of descriptive research are… • Making models • Dissections • Observing animals in the wild
For example… How do the survivors of a disaster react to the disaster? No variables; data is based on watching and talking to survivors
Experimental research is… • The manipulation and control of variables
What are the three types of variables? • Independent variables • Dependent variables • Controlled variables • Also called constants
Independent variables are… • What is being tested • What is being changed • The difference between the groups • The ‘cause’ of a change
Dependent variables are… • What is observed • What is measured • The data • The ‘effect’ caused by the independent variable
Controlled variables are… • Things that could change, but don’t • Kept constant by the scientist • Allow for a fair test
So an experimental question has to indicate the variables • How the independent variable will AFFECT the dependent variable • What the EFFECT of the independent variable will be on the dependent variable
For example… • How does the temperature of ocean water affect the speed of a hurricane? • Independent variable • T of ocean water • Dependent variable • Speed of a hurricane
Predictions • Educated guesses about what will happen during an investigation • Based on prior knowledge (observations, background research, etc)
For example… People in disasters will react by trying to help others as much as possible. This is a PREDICTION because it’s a guess about what you think will happen.
Hypothesis(plural – hypotheses) • Special kind of prediction • What makes it so special??? • It’s a guess about the VARIABLES & their relationship, in particular, • How will the independent variable affect the dependent variable?????????
How to write a hypothesis • Use an If, Then statement • IF the independent variable changes, THEN the dependent variable changes • This type of sentence shows what the IV will do to the DV
For example… • IF the T of ocean water increases, THEN the speed of a hurricane will increase. • This shows the expected relationship between the independent variable (the T of ocean water) and the dependent variable (the speed of a hurricane) • If the T of ocean water changes, it will cause the speed of a hurricane to change too.
The null hypothesis • A statistical procedure • Stated as if there will be no relationship between the variables
For example… • There is no relationship between water temperature and the speed of a hurricane
Planning the investigation – Experimental Design • You absolutely, positively have to know what the variables are! • What you are changing • How you are changing • What you are measuring • How you are measuring • Repeated trials • Data tables
Data tables? • Numerical (quantitative) data organized in rows and columns • The specific independent variables are listed • The number of trials are listed • Blanks are left for the data (dependent variable) to be filled in
Analyzing the data • Reduce the data • Do something to make the amount of data smaller • Central tendencies • Mean (average) • Median • Mode • Range • frequency
Analyzing the data • Graph the data • Lets us see trends, patterns, relationships, comparisons • Bar graphs • Let us compare data • Line graphs • Let us see trends or changes • Scatter plots • Shows correlations or associations between variables
Bar graph This shows a comparison of the types and amounts of trash found on a beach
Line graph This shows a change in grade point averages; the trend is an increase in GPA
Scatter plotPositive Correlation An increase in the variable on the X-axis is associated with an increase in the variable on the Y-axis
Scatter plotNegative Correlation An increase in the variable on the X-axis is associated with an decrease in the variable on the Y-axis
Scatter plotNo Correlation Random data points – there is no association between the variables
Conclusions • How we sum up the investigation • Does the data support the hypothesis? • If it does – we accept the hypothesis • If it does not – we reject the hypothesis • All back up what you say with data • Evidence • Discuss issues or problems with the investigation • Discuss the importance or relevance of the investigation
Communicate what you know • Finding out something new doesn’t do anyone any good unless the new knowledge is shared • Journals & magazines • Presentations