What is Experimental Research?

Experimental research is… The manipulation and control of variables

Speaking of variables….

What are the two types of variables? Independent variables Dependent variables

Independent variables are… What is being tested? What is being changed on purpose?

Dependent variables are… What is being observed? What is being measured? The data The ‘effect’ caused by the independent variable

“Constants” are… Variables that could change, but don’t Must be 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 have on the dependent variable

For example… How does the temperature of ocean water affect the speed of a hurricane? Independent variable Temp of ocean water Dependent variable Speed of a hurricane

Hypothesis Educated guess about what will happen during an investigation Based on prior knowledge (observations, background research, etc)

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 Temp 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.

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

Title Describing the Data Trial Variable 1 Variable 2 Variable 3 1 2 3 4 5 Average

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 Lets us see trends or changes

This shows a comparison of types and amount of trash on a beach. Bar graph This shows a comparison of types and amount of trash on a beach.

Line graph This shows how the grade point average has been changing over several years. The trend is an increase in GPA.

Draw a Conclusion 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/Share Results Finding out something new doesn’t do anyone any good unless the new knowledge is shared Journals & magazines Presentations