BIO 1017 lab 1

a relationship between the independent and the dependent variable. Correlations are often used as support for hypotheses.

A correlation is

Even though the hypothesis can be falsified, it can never be proved true. The evidence from an investigation can only provide support for the hypothesis.

A scientifically useful hypothesis must be testable and falsifiable (able to be proved false). To satisfy the requirements that a hypothesis be falsifiable, it must be possible that the test results do not support the explanation

that stands the test of time may be elevated to the status of a principle. A hypothesis that has been tested with a significant amount of data

A theory

the null will be accepted or rejected. The alternative hypothesis is accepted only if Ho is rejected.

After analysis of the actual test results

use enough experimental units in each group so that any differences in the effects of the treatments can be distinguished from chance differences between the groups

Calculate replicates. replication in experimental design

in which the independent variable is held at an established level or omitted

Control

the group that is not subject to the independent variable; does not receive the experimental treatment

Control group

to allow the scientist to decide whether the predicted effect is due to the independent variable.

Control serves

a logical process by which a prediction is produced from a general statement (hypothesis).

Deduction is

y-axis

Dependent variable on a graph

Temperature is certainly a well-defined, measurable, and controllable factor, but morality of behaviour is not scientifically measurable. Thus, no experiment can be performed to test the question.

Do excessively elevated temperatures cause people to behave immorally? Could a scientist investigate this question?

controlled variable, independent variable, dependent variable

For the example above, the _______ is the requirement that all of the observed organisms be mammals; the ________ is the classification of each of the observed mammals into one of the three main groups of mammals (monotremes, marsupials, and placental mammals); and the __________ is the method of reproduction - live bearing or egg laying - for each mammal observed.

There will be a difference

Ha

There will be no difference

Ho

never completely accept or reject a hypothesis; all you can do is state the probability that one is correct or incorrect.

However, you can

A testable prediction, often implied by a theory

Hypothesis

experimental group that is subject to the independent variable and a control group that is not.

In an experiment of classical design, the individuals under study are divided into two groups:

experimental group would receive a high iron diet, control group would receive an average iron diet. The independent variable is the increase in the iron content of the diet; controlled variables are the same room temperature, water availability, and housing conditions; the dependent variable is the amount of growth.

In an experiment to test the effect of iron on the growth of weaning rats, the weaning rats would be separated at random into two groups and raised on a balanced diet except for the iron content.

experimental group, control group, independent variable, controlled variables, dependent variable

In an experiment to test the effect of iron on the growth of weaning rats, the weaning rats would be separated at random into two groups and raised on a balanced diet except for the iron content. The ________ would receive a high iron diet, and the _______ would receive an average iron diet. The _________ is the increase in the iron content of the diet; _________ are the same room temperature, water availability, and housing conditions; and the ________ is the amount of growth.

x-axis

Independent variable on a graph

a logical process by which all observations are combined and considered before producing a general statement

Induction is

The value that is set for the independent variable. The value may be based on previous research and preliminary measurements.

Level of treatment

Variables can be described for the non-experimental approach as well. For the example above, the controlled variable is the requirement that all of the observed organisms be mammals; the independent variable is the classification of each of the observed mammals into one of the three main groups of mammals (monotremes, marsupials, and placental mammals); the dependent variable is the method of reproduction - live bearing or egg laying - for each mammal observed.

One of the most important principles in biology, Darwin's theory of natural selection, was developed by this non-experimental approach. For example, testing the prediction that 'the three main groups of mammals do not all bear live young,' would require observation of reproduction in as many mammals as possible from each of the three groups.

A statement of what will happen next in a sequence of events.

Prediction

An established or official way of doing something

Procedure

Scientific investigations are not valid if the conclusions drawn from them are based on one experiment with one or two individuals. Generally, the same procedure will be repeated several times (replication), providing consistent results. Notice that the scientists do not expect exactly the same results inasmuch as individuals and their response will vary. Results from replicated experiments are usually averaged and may be further analyzed using statistical tests.

Replication

Experimental design, to design an experiment or to make pertinent observations to test the prediction made from the research hypothesis. \One begins with statements of a null hypothesis (Ho) and an alternative hypothesis (Ha).

Scientific method fifth step

to formulate a prediction. If the research hypothesis is accurate, then a prediction based on the research hypothesis should also be accurate. This is deductive or "if-then" reasoning.

Scientific method fourth step

The second step is to ask a question about these observations. The quality of this question will depend on how carefully the observations were made and analyzed.

Scientific method second step

conclusion, you use the results of the experiment or pertinent observations to test your prediction. If your prediction does not occur, then you must accept the null hypothesis. If your prediction does occur, it indicates that you may reject the null hypothesis and accept the alternative hypothesis.

Scientific method seventh step

Data analysis. You collect all your data and analyze the results. This involves interpretation of tables, graphs, etc. From this data you form your conclusion.

Scientific method sixth step

hypothesis This is a general statement of the answer to the question and is derived by inductive reasoning.

Scientific method third step

a process that tests possible answers to questions about nature in ways that can be duplicated or verified.

The scientific method is

careful observations. An investigator may make observations from nature or from the written words of other investigators which are published in books or as research articles in scientific journals

The scientific method starts with

Ho- no change will occur, Ha- change will occur. If/then prediction relation statements to independent/dependent variables.

Utilize the same format for H&P:

level of treatment

appropriate values to use for the independent variable 10mg 15mg 20mg for a medication

are all the other conditions and events, which the investigators attempt to keep the same.

controlled variables

is the condition or event that may change due to the independent variable

dependent variable

Prediction: If water temperature affects bacterial growth on shower curtains, then hot showers would lead to increased bacterial growth on shower curtains. HO: There will be no difference in the growth of bacteria on shower curtains with only hot showers. HA: There will be a difference in the growth of bacteria on shower curtains with only hot showers.

example: Prediction:

the group that is subject to the independent variable; receives the experimental treatment

experimental group

is the condition or event under study.

independent variable

test of a prediction is not an actual experiment but relevant observations

non-experimental approach

contributed to your results. It might be a coincidence or the effect of some unforeseen and thus uncontrolled variable.

other factors may have