Investigating+Scientifically


 * // Human Biological Sciences Investigating Scientifically //**


 * // Summary of Chapter 2 Book 1 Human Perspectives and Chapter 1 Book 2 //**

A ** hypothesis ** is a tentative proposal made to explain certain observations. Any hypothesis requires investigation to collect evidence that will support the hypothesis. A good hypothesis: cause disease (second variable).
 * Scientific method **
 * 1. ** recognise a problem and define a question
 * 2. ** collect as much information as possible relating to the problem
 * 3. ** propose a hypothesis—a possible explanation for the problem
 * 4. ** test the hypothesis using an experiment
 * 5. ** analyse and interpret the data collected from the experiment
 * 6. ** draw conclusions about whether the hypothesis was supported or disproved
 * 7. ** report on the investigation.
 * 1. ** is usually a definite statement—not a question
 * 2. ** is short—it is much easier to test a simple hypothesis than a complex one
 * 3. ** has a single idea that can be tested
 * 4. ** usually links two variables—for example, Pasteur’s hypothesis that microorganisms (one variable)


 * Variable ** any factor that may change during an experiment


 * Independent variable ** in an experiment, the factor that is being investigated; the factor that is deliberately changed to determine its effect; also called the experimental variable or the manipulated variable


 * Dependent variable ** in an experiment, the factor that changes in response to changes in the independent variable; also called the responding variable
 * Control **a procedure carried out to give a comparison in an experiment

The is group should be selected randomly when possible (reduce bias) and large as possible (consider biological variation) and when results are averaged reduced effect of error.
 * Sample Group/Size ** the group or number of subjects under the influence of the experimental variable


 * Controlled experiment ** an experiment in which there are two almost identical set-ups, the only difference between them being the one variable that is being tested


 * Controlled variables ** those variables that are kept constant (controlled) in an experiment


 * Uncontrolled variables ** are variables that were not kept the same for the control and experimental groups in an experiment. They may have been overlooked by the experimenter or they may have been impossible to control.

students are 174 and 176 cm in height’ is taller than student B’.
 * Data ** observations and measurements; the results of an experiment. Data from an investigation can be one of two types:
 * •** ** quantitative data **—expressed in numbers and usually involving measurement; for example, ‘the
 * •** ** qualitative data **—observations that do not involve numbers or measurement for example, ‘student A


 * Conclusion ** summation of the results, relate results to hypothesis- state results, state significance of results, state if results support or rejects the hypothesis


 * Repetition ** performing the same experiment many times


 * Reliability ** the extent to which an experiment gives the same result each time it is performed
 * Validity ** the extent to which an experiment tests what it is supposed to test
 * Scientific model ** a simplified representation of a complex idea or process
 * Observation ** the use of the senses, sometimes with instruments that enhance the senses, to gather information


 * Experimental Error ** Results of experiments always contain errors. Experimental error it is also one of the reasons that favourable experimental results **cannot prove** a hypothesis. They can only provide support for it.


 * Human error ** is simply a mistake; for example, incorrectly reading the scale on an instrument, spilling some liquid before measuring the volume or making a mistake in a calculation.
 * Random errors ** are unpredictable and occur in all experiments. They occur because no measurement can be made with absolute precision. For example, if you are using a stopwatch to time how long it takes a person to carry out a particular task, sometimes you will stop the watch a little early, sometimes a little late.


 * Systematic errors ** occur because of the way in which the experiment was designed. In this case a measurement will //always// be too high or too low. Systematic errors cannot be reduced by averaging; the only solution is to change the experimental procedure. Statistical tests are available to try to determine whether differences in measurements


 * Investigating Humans /Ethical problems **


 * Ethics **are a set of moral principles or values; ** ethical behaviour ** is behaviour that conforms to those principles or values. In scientific research, particularly research with human participants, many ethical issues arise. Some of the principles that an investigation must satisfy if it is to be ethically sound are:


 * 1.** //Voluntary participation//
 * 2.** //Informed consent//
 * 3.** //Risk of harm//
 * 4.** //Confidentiality//
 * 5.** Anonymity

The code sets out terms any use of animals in research or teaching should be:
 * Use of Animals **
 * •** valid
 * •** humane
 * •** justifiable
 * •** considerate.


 * Placebos ** are used in research into the effectiveness of medical treatments such as a new Medicinal drug. In the case of a drug trial, a **placebo** is **//an inactive substance//** that looks like the real medication. One group of subjects, the experimental group, takes the drug that is being tested and the other group, the control, takes the placebo. The patients who are given a placebo often show an improvement in their condition even though the placebo is inactive. This is called the **placebo effect**. It is thought to occur because of the patient’s belief that the placebo is a real therapy that will bring about improvement. If, in a trial of a therapy, the test group show a better response than the control group, despite the placebo effect, the therapy can be assumed to have been effective.
 * Blind Experiments ** When the subjects being test do not know they are the test group. The **blind** method is a part of the [|scientific method], used to prevent research outcomes from being influenced by either the [|placebo effect] or the [|observer bias] . Blinded research is an important tool in many fields of research, from [|medicine] , to psychology and the social sciences, to [|forensics].
 * Double Blind ** experiment neither the individuals nor the researchers know who belongs to the control group and the experimental group.


 * Presentation of data **

column and those for the dependent variable are in the right-hand column or columns. This is not a definite rule. The most important consideration is that the table is easy to understand.
 * // Tables //**: Rules you should follow:
 * •** The table must have a title. The title usually states the variables investigated in the experiment.
 * •** Data are presented in columns. Usually the data for the independent variable are in the left –hand
 * •** Each column has a heading that names the variable and the units in which it is measured.

A useful way to present data so that they can be understood easily is to draw a graph. A **graph** shows how changes in one variable affect a second variable. For example, if the weight of a baby is measured every month for 2 years, the data can be plotted on a graph. Time (in months) is one variable; it affects the other variable, weight. In this case, time is called the **independent variable**. Weight is the **dependent variable**,
 * // Graphs //**

A line graph, the most commonly used type of graph in science. Other types of graph that you will come across, and may be required to draw, are bar or column graphs, and histograms.
 * // When drawing a graph it is important to remember to //** :
 * •** label the axes with the names of the variables
 * •** indicate the units in which each variable is measured
 * •** give the graph a title that summarises the relationship illustrated by the graph
 * •** use equal intervals of units on each axis.
 * Bar** or **column graphs** represent data by rectangles of equal width with spaces

A scientific **model** is a simplified representation of an idea or process. Once a model has been developed it can be applied to a number of situations. Scientific models oft en have to be modified as new data are collected. .
 * Scientific models **
 * Types of investigation **


 * Observation ** is an essential part of science and any investigation, regardless of the procedure used, will involve some form of observation. In investigations based on observation, scientists are looking for patterns. When a pattern becomes evident it may be possible to draw tentative conclusions.

A **survey** is a process of systematically collecting, analysing and interpreting information about an aspect of a study. Surveys are usually designed to collect data from a large number of subjects. The information may be collected using a questionnaire or by interview. Using the large amount of information collected, the researcher can then look for patterns in the data.
 * // Surveys //**

Trial and error sounds like a random process but when used in scientific research it is systematic. The process involves one attempt to solve a problem being followed by another. Each trial is recorded and the results allow the investigator to gradually home in on the solution to a problem. A ** case study ** is an in-depth investigation of one particular person or situation. They are frequently used in areas such as education and business management. However, case studies may also be useful in some areas of science. When an investigation has been completed, the findings need to be made known to others. This is usually done by a written report. Reports are a very important part of communication in science. Scientists inform others of their research by publishing a report in a scientific journal
 * // Trial and error //**
 * // Longitudinal studies: //**A longitudinal study is one that is conducted over a long period of time. It is similar to a case study but is more prolonged. Longitudinal studies may take place over many years, even decades.
 * Reporting **


 * // Validity and reliability of results //**

An experiment is **valid** when it tests what it supposed to test. Some scientists were testing the hypothesis that ‘consumption of junk food affects memory’. They fed one group of young rats on fatty food for 12 weeks, with another group being put on a low fat diet. The rats’ memories were then tested using an activity that involved pressing a lever. The rats fed on junk food were more forgetful so it was concluded that the hypothesis was supported. This experiment did not test what it was supposed to for two reasons. Experiments can also be invalid if there are uncontrolled variables—that is, if there are factors that could affect the result of an experiment that are not kept the same for the experimental and the control set-ups. When experimenting with humans it is often very difficult to design a valid experiment because it is hard to control all of the variables.
 * 1.** Testing one species, rats, will only demonstrate the effect on the memory of rats, not any other species.
 * 2.** Laboratory rats, kept in cages for long periods, may have memories affected by boredom and isolation.

Repetition and replication are used to make sure that results are reliable but they do not improve the accuracy of the experiment.
 * Reliability ** is the extent to which an experiment gives the same result each time it is performed. The measuring instruments used in the experiment must also be reliable; that is, give the same measurement each time they are used. For example, you may have a set of bathroom scales that give three different weights when you step on them three separate times. Those scales are unreliable, and if used in an experiment would make the results unreliable.


 * Analysing results **

Data from an investigation can be one of two types: students are 174 and 176 cm in height’ is taller than student B’. Wherever possible, you should design an investigation so that results are quantifiable. Numerical results can be ranked, averaged and manipulated in other ways. They can also be summarised using graphs.
 * // Quantifying results //**
 * •** ** quantitative data **—expressed in numbers and usually involving measurement; for example, ‘the
 * •** ** qualitative data **—observations that do not involve numbers or measurement; for example, ‘student A

If you have designed an experiment to give quantitative data, you will end up with a mass of figures that you must interpret. In a controlled experiment you will have to compare the control and the experimental results. There are some simple calculations that you can do to make the numbers more meaningful.
 * // Processing data //**

In science a description of a set of numbers almost always includes a measure of its centre, or its **average**. Averages are a very common and simple way of handling sets of numerical data. The average that is most often calculated is the **arithmetic mean**, often just called the mean. To calculate the mean of a group of measurements, you add up all the measurements in the group and divide by the total number of measurements. Sometimes in a set of measurements there will be values that are well beyond the range of the rest of the measurements. Such values are called **outliers**. Means are affected by outliers since a very high or very low outlier value would make the mean higher or lower than it would be without the outlier included. Outliers may be the result of mistakes in measurement, the failure of equipment or other errors. If the outliers are clearly the result of an error, they may be excluded when the mean is calculated.
 * Averages **

A measure of the centre of a group of numbers can be misleading. The mean gives us no idea about whether all the values are clustered around the centre or whether there is a very wide spread from the highest to the lowest value. Any description of a set of numbers should therefore include both a measure of the centre and a measure of the spread. The simplest way to indicate the spread is to quote the **range**; that is, the highest and lowest measurements in the group. For example, we could say that the heights of students in a Year 12 class ranged from 151 to 183 cm with a mean of 171 cm. Scientists use a number of other measures of spread, such as quartiles or standard deviation, but for your investigations range should be sufficient.
 * Ranges **

A **ratio** is a numerical statement of how one variable relates to another. That is, it is a comparison of two numbers. Ratios are written as two numbers separated by a colon. For example on a standard TV screen the ratio of width to height is 4:3; thus, if the width is 40 cm the height is 30 cm, if the width is 60 cm the height is 45 cm and soon. Widescreen TVs have a ratio of 16:9. A **rate** is a special kind of ratio that shows how long it takes to do something. For example, a good athlete can run 10 000 metres (10 km) in around 30 minutes This is a rate of 1 km/3 minutes or 20 km/hour. The rate at which something occurs is much more meaningful than a simple count of how often it occurs. If you were investigating the effect of exercise on breathing, counting a person’s breaths would be meaningless unless we knew how many breaths there were in a given time. That is, we would need to know the breathing //rate// in breaths per minute.
 * Ratios and rates **

In Western Australia in 2007, 15- to 19-year-old males made up 7.2 per cent of the population; females of the same age made up 6.9 per cent of the population. This means that for every hundred people in the population 7.2 (or 72 per thousand) are 15- to 19-year-old males and 6.9 (69 per thousand) are 15- to 19-year-old females. Another way of looking at it would be to say that for every 69 girls aged 15 to 19 in Western Australia there are 72 boys aged 15 to 19.
 * Percentages **
 * Per cent** means per hundred. Percentages are used to express how large one variable is in relation to another, for example, the amount of fat in a food. If a breakfast cereal were labelled as containing 1.5% fat, that would mean that 100 grams of the cereal would contain 1.5 g of fat.

Calculating a percentage increase or percentage decrease is often a good way of helping people to understand changes in a variable over time. To calculate percentage change: then **//divide//** by the old value (120 kg) This can be written as a formula: new value – old value × 100 = percentage change If the percentage change is positive, it indicates an increase; if the change is negative, it indicates a decrease.
 * Percentage change **
 * //subtract//** the old value (120 kg) from the new value (107 kg),
 * //multiply//** the result by 100 and add a per cent sign (%) to it. That is the percentage change.


 * Frequencies **


 * Frequency** is the number of times an event occurs. A table of the data collected is called a **frequency distribution** or **frequency table**. Frequencies can also be presented graphically as a histogram.

An extensive examination of the literature at the start of an investigation allows the researcher to fully grasp the information that is available relating to the problem under consideration. This review also allows the results to be seen in the context of what is already known. Research done by others can also be used to support or confirm what has been discovered in the investigation. Demonstrating how your findings relate to what was already known will give credibility to your research and will add to the body of knowledge on the subject under review.
 * // Reference to the work of others //**


 * Reporting **

When an investigation has been completed, the findings need to be made known to others. This is usually done by a written report. Reports are a very important part of communication in science. Scientists inform others of their research by publishing a report in a scientific journal. There are thousands of scientific journals, some of which deal with a very narrow field of science. Examples are //Nature//, //Science//, //Journal// //of Musculo-Skeletal Research// and //Journal of Genetics//. The editors of scientific journals use a process called **peer review** to make sure that the report is worthy of publication. A submitted report is sent to one or more scientists who are experts in the field and who may or may not recommend publication. This process is important, as it helps to keep scientific literature free of incorrect, bogus or misleading information. A scientific **report** includes a description of an investigation, the results that were obtained and any conclusions that can be drawn from the results. The description of how the investigation was done must be sufficiently detailed to allow other scientists to repeat the experiment. It is common practice for scientists to repeat experiments that others have performed. If the results obtained are not the same as those for the original experiment, any conclusions that may have been drawn are worthless. Reports follow a fairly standard format, similar to that described below.

Reports may be written using the following headings: specialised items of equipment tested of the investigation suggest areas that need further investigation information that have been referred to in the report have provided funds for the research.
 * // Scientific report format //**
 * • title** and **name** of the author or authors
 * • introduction**, stating the nature of the problem that was investigated and the hypothesis that was tested
 * • materials and equipment**, listing the apparatus used, particularly any
 * • procedure**, describing the exact method that was used to carry out the investigation
 * • results**, often presented as tables, graphs, diagrams or photographs
 * • discussion**, including comments about the results and the way they relate to the hypothesis that was
 * • conclusion**, summarising the most important parts of the discussion and stating the success or otherwise
 * • further research**, as scientific investigations often raise more questions than they answer—many reports
 * • references**, which consist of a list of any reports, books, journal articles, websites or other sources of
 * • acknowledgments**, which are to people who have helped with the investigation or to organisations that


 * The Discussion **

The most important part of a report, and the longest part, is probably the discussion. The discussion is about the results and the method used to obtain the results. The discussion needs to be very thorough and to address all aspects of the research. Here is a checklist of questions that could be answered in the discussion section of a report: This is not an exhaustive list of questions and when writing a report you will be able to think of other points that need to be discussed.
 * •** Were there any defects in the design of the investigation or in the procedure?
 * •** Were there any results that were different from those expected?
 * •** How do the results fit into the broader context of what is already known about the topic?
 * •** Are there any practical applications for the results?
 * •** Do the findings relate to any earlier work in the same area?
 * •** Did the results support the hypothesis or did they indicate that the hypothesis was incorrect?
 * •** Were there any limitations in the research?
 * •** Could the investigation have been improved in any way?
 * •** Were there any variables that could not be controlled?
 * •** Was there any bias in the results?
 * •** Is there any information available from other reliable sources that would support the results?
 * •** Is there a need for further research to clarify any of the results?