hypothesis and iv and dv

How Science Works

Experimental method

Experimental Process

1. Ask questions and develop theories about how, why and where things happen

2. Develop these into a specific hypothesis (predictions)

3. Design & Carry out research to test these theories – what happens when we try it out?

Experimental Process

Findings support or refute theory = refine theory

Hypotheses• 2 types:

Experimental Hypothesis(Alternative Hypothesis)

- A prediction of the outcome

Null Hypothesis

-Findings are due to chance

-There is no relationship or difference as predicted

Try writing an Experimental & Null hypothesis for these possible

studies1. A study that aims to look at the effect of music

on concentration

2. A study that aims to look at the amount of TV a child watches and their behaviour at school

3. A study that aims to see whether a task, such as counting backwards from the number 15 after seeing a list of letters, will affect the ability to recall of those letters

Experimental Hypotheses

You may wish to predict the direction of the effect = Directional / One-tailed

e.g.– Students’ performance will improve with practice– Eating chocolate will increase happiness– Taking regular exercise will decrease risk of heart

disease

• Alternatively, you can just say that there will be an effect = Non-directional / Two-tailed

Examples

1. Students remember more words when recalling them in the same location in which they were learnt than when in a different location.

2. Recall of a story is affected by the length of time since hearing the story.

• Experiments are one of the most commonly used methods in psychology

• An experiment is a research method in which the researcher – the experimenter – has a high degree of control.

• The experimenter controls/manipulates the independent variable (IV) and measures the dependent variable (DV)

Experimental Process

Example

• If we were to conduct an experiment on whether television distracts students from studying, what would be the IV and the DV?

HINT:Look for what is being measured (DV)

first, IV is then easy to identify!

• Both IV & DV MUST be measurable = Operationalise

• There are usually two values of the IV e.g.– Noise or no noise– Smoker or non-smoker– Male or Female

• These determine the conditions of the experiment

• The conditions can be arranged in several different ways (There can be more than 2 conditions)

Other variables• What else might affect the study?

• Any variable (except for the IV) that can influence your findings = extraneous variables

E.g. Participant Variables = age, gender,

experience, emotionSituational Variables = noise, light, time

of day, crowds, interruptions

• If an extraneous variable is NOT controlled for and impacts the results =

Confounding variable