Working with Scientific Data.pptx

WORKING WITH SCIENTIFIC DATA Chapter 1 Sylvia Park Data Data is the term given to all the observations and measurements that can be used to describe something. Data Quantitative Qualitative Types of Data Quantitative...

WORKING WITH SCIENTIFIC DATA Chapter 1 Sylvia Park Data Data is the term given to all the observations and measurements that can be used to describe something. Data Quantitative Qualitative Types of Data Quantitative Qualitative Measurements that are Data which can only be written as numbers with described in words. units attached to them. Colour of eyes Temperature States of Australia Height Rock types Coordinates Animals found in the area People in the room Types of Data – by methods First-hand data Second-hand (Secondary) data Data what you or your Data that comes from the team personally find out work of other people. by running your own Information found on the experiments. internet, books and videos Experiments etc Can also be obtained by Surveys interviewing experts Collecting your own data Mistakes Errors Things that can be are not mistakes avoided if you take a little Small and unavoidable more care. variations (changes) that spillages naturally occur in using wrong equipment measurements. wrongly read an instrument will always occur no incorrectly write or copy the measurements down matter how careful you are (nothing is exact) Common forms of error Parallax error Looking at markings at different angles causing slightly different readings. Common forms of error Reading error Measurements falling between the markings of a measuring device so you need to estimate your measurement. Common forms of error Instrument error Sometimes an instrument may be faulty and will not give correct readings (a metal ruler expands when hot or contract when cold). Common forms of error Human reflex Everyone has different reflex times so they will measure times slightly differently using a stopwatch. Common forms of error Zero error An instrument such as a balance should read zero when nothing is placed on it (they can be adjusted to read zero once more). Importance of taring When you tare an electronic balance, you are re-setting it to read zero when something like a beaker is placed on it. By doing this, the reading will only show the mass of the content added (no need to subtract the mass of the beaker from the total mass). Improving first-hand data Errors always exist. No-one is wrong (unless they made a mistake) and everyone’s measurement is ‘correct’. One easy way of improving the accuracy of your data is to repeat your measurements so that they can be compared and obvious mistakes can be eliminated. Once a collection of different measurements is taken, an average or mean can be obtained. Finding averages To find an average: 1. Delete the highest and lowest measurements if they are too much apart from other measurements. These are called ‘outliers’. 2. Add the rest of the ‘good’ measurements. 3. Divide by how many ‘good’ measurements were taken. Uncertainty To estimate how big the error might be. Scientists allow a little ‘give and take’ by showing the error as ± (plus or minus). Scientists usually make the error half of the smallest of the divisions of the instrument they are using. Units In science, most of your measurements will use metric or SI (Système Internationale) units. Length – metres (m) Mass – kilograms (kg) Liquid volume – litres (L) Time – seconds (s) Temperature – degrees celcius () Weight and Force – newtons (N) Energy – joules (J) Reaction Time Experiment Pearson (p.9) 1.REACTION TIMES Internet reaction times Go to the following website http://reflextest.net/ Play the following reaction time games 5 times and record your results in your book. Colours Stop the clock Click ‘More reaction time tests’ Image Test Letter ‘X’ Describe what happened. Explain why you think this happened. Describe vs Explain Describe: provide characteristics and features My reaction time improved/unchanged/worsened over the 5 trials. Explain: provide the cause and the effect make the relationships between things evident provide why and/or how My reaction time improved as I became more familiar with the game with repetition. The more I practiced the game, the better my reaction time became. Improving second-hand data Second-hand data is easy to find but is not always accurate. How old is the data? The imprint page shows who published the book or magazine and when it was published. Websites should have the date they were created and last updated at the bottom of their opening pages. The need to compare All second-hand-data should be checked against data found in other sources. If it agrees, then it is probably accurate. Resources lists As scientists, we must be ethical in whatever we do. It is unethical for a scientist to pretend that data is theirs when it actually came from the work of someone else. A resources list (sometimes called a bibliography) is a list of every textbook, encyclopedia, scientific journal and webpage from which you collected information or used to check the accuracy of data you found. Where did it come from? Usually reliable May not be reliable Encyclopedias Commercial businesses (.com) Scientific journals Networks (.net) Science textbooks Some organisations (.org) Science magazines Gossips Educational institutes (.edu) Celebrity magazines Government (.gov or.gov.au) Wikipedia Some organisations (.org) Country Domain Country domains USA None Australia.au United Kingdom.uk Canada.ca India.in United Arab Emirates.ae Practical reports A prac report should include the following sections. Heading Write an appropriate heading for the experiment. Include the name and date(s) of the investigation and a list of partners who were in your team. Purpose/Aim One or two sentences briefly describing what you are trying to achieve through this experiment. e.g. To investigate/determine/measure… Hypothesis A statement of an educated guess about what might happen in an experiment and what might be found out. (e.g. Boys have faster reaction time than girls at the same age.) Materials A comprehensive list of all chemicals and the equipment used. Risk Assessment Preferably written in a table to show the list of possible hazards in the experiment with its corresponding precautions to be taken. Safety issues Precautions Bunsen burner – fire, skin burn Tie the hair back; keep all combustible materials away; do not touch any equipment which may be still hot Procedure A sequential (1, 2, 3 …) description of everything that you did in the investigation. A labelled diagram is a good way to describe how equipment was set up. Results Record your observations and/or measurements. Tables and/or graphs can be included. Practical review/Discussion May involve answering a set of questions. Discuss what happened and why it happened. Describe problems encountered and what was done to overcome them. State whether your hypothesis was supported by the results or not, suggesting ways of improving the investigation. Conclusion A brief summary of what you found out in the investigation (answer the aim). Ethical guidelines Be safe – assess all risks Be careful – avoid mistakes Be honest – run fair tests Be respectful – respect the work of others Take care of the environment – dispose all materials appropriately Take care of animals – do not carry out unnecessary experiments on animals Graphing Data Graphs are better than tables at showing patterns in data. Sometimes your data will produce perfect straight lines or perfect curves. If your data is continuous data and it looks more like a dot- to-dot picture, then try and construct a line of best fit or curve of best fit. Types of Graphs Shoe size and body mass of 10 men The Pendulum and Length (p.36 Pearson 8) Aim: To test the effect of the length of a pendulum on its period. Hypothesis: Materials: Risk Assessment: Procedure: Results: Practical Review: Conclusion: Testing Absorbency of Paper (p.36 Pearson 8) Aim: What is going to be your controlled, independent and dependent variables? Hypothesis: Materials: Risk Assessment: Procedure: Results: Practical Review: Conclusion: