(IES) Collecting and Analyzing Data Lesson

Collecting and Analyzing Data

When science students are collecting data for a science project, they should be aware of these basics steps: precision, accuracy, and reliability. After students collect data, it is also important that they can interpret and present the data in the form of a graph or report. These two skills represent the last two parts of the scientific method involved in doing science experiments.

Although collecting and analyzing data are listed in the investigation, be aware that you will begin collecting data the moment you pose a question. Even though we list the scientific method using 1-5 remember questioning, observing and sometimes even changing things are all part of the process. However, it is really critical that you are keeping a log with your data and with your notes.

Staying Organized

A logbook is a crucial part of any research project. It is a detailed account of every phase of your project, from the initial brainstorming to the final research report. The logbook is proof that certain activities occurred at specific times.

You will want to choose a method to maintain your information. Keep in mind whether you choose to use an electronic device or a composition book you must be diligent to maintain your logbook and to record everything.

If you are keeping a hardback or composition logbook these guidelines will help you stay organized. (If you are preparing for a Science Fair make sure you check the rules and guidelines for record keeping established by the organizers of your Science Fair).

  1. Write your name, your teacher's name and your school on the outside cover, and on the back cover. This will help get your logbook back to you if you misplace it. Your logbook should be sturdy. Loose papers are sure to get lost.
  2. The first page should be your title page. Include the title of your study, your name, and your school.
  3. Leave a blank page between the title page and the first page of your log.
  4. Number the pages in your logbook, unless they are pre-numbered.
  5. Create a new entry for each day of your experiment. Note the date and time. Clearly detail your actions that day, including results that were observed, problems encountered, solution to previous problems and actions taken to further the experiment.
  6. Once your investigation is complete go back to the page you left blank after the title page and create a table of contents.

Measurement

Regardless of the unit of measure you choose to use accuracy, and precision are important to consider as you collect your data. Sometimes instrument markings do not have small enough increments to measure accurately. The difference between a measurement and the dimension's actual value is called the error of the measurement. Error in measurement is one of the limitations of science. Every scientific measurement contains error, no matter how good the instrument and the observer may be.

How are accuracy and precision different?

Accuracy evaluates how close a measurement is to the actual value. An instrument's accuracy will depend on how well it was manufactured and constructed.

Precision evaluates how exactly a measurement is made. Precision will depend on the scale calibrations on the instrument used to measure.

What this means for you and for all scientists is that records and recording data should include the instrument that was used to attain the measurement.

Analyze, Conclude and Share

Key information to consider when you are ready to analyze your data.

Double check your data. Try to look at the results of your experiment with a critical eye or ask a critical friend to look over your data.

Consider these things:

Have you calculated an average for the different trials of your experiment, if appropriate?

Have you clearly labeled all tables and graphs including the units of measurement?

Did you place the independent variable on the x-axis of your graph and the dependent variable on the y-axis?

Take some time to carefully review all of the data you have collected from your experiment. Use charts and graphs to help you analyze the data and patterns. Did you get the results you had expected? What did you find out from your experiment?

Really think about what you have discovered and use your data to help you explain why you think certain things happened.

Calculations and Summarizing Data

Sometimes a scientist will need to calculate the raw data in different ways in order to reveal the patterns and to interpret the numbers. You want to find the best and most effective way to summarize the data from all the trials of your experiment. A common calculation is to average the trials from each group, but you could choose to look at percentages, ratios, or even the error of measurement.

Graphs

After all the hard work you have put in your experiment you want to be able to communicate your findings effectively. Using a graph is one way to display your data so that it can be readily interpreted. Depending on the experiment and the data you will need to decide which type of graph is the most appropriate to use.

Here is a list of common graphs to consider:

  • histogram
  • bar graph
  • pie chart
  • scatter plot
  • time-series plot
  • xy-graph

There are others but these are commonly used.

Practice Reading Data

Price for Mowing the Lawn: Mark-10 Steven-12 Martin-10 Lance-15 Greg-12

Keith and his family have just moved to a new town. In his old neighborhood he mowed the grass for ten of his fourteen neighbors. It was perfect! He mowed two yards a day Monday thru Friday and he still had the weekends off. He took great pride in how the entire neighborhood looked so well manicured. But, when his father received a great promotion his family had to move.

Keith is hoping to start over in his new neighborhood and is making a plan for how he will market his services. He knows in this town and this neighborhood he will have a lot more competition than in his previous town. He asks some of the students at school his age how much they charge to mow the lawn. The list titled Price for Mowing the Lawn is the results of the data he collected.

Answer the following questions as practice for reading data.

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