Aims and Hypotheses

• An aim states the overall intention of the research.
• Hypotheses are precise statements or predictions about what the researcher expects to find.
• An experimental hypothesis is used for research using experimental methods like lab or field experiments.
• An alternative hypothesis is used for non-experimental research methods like correlations or observations.
• A directional hypothesis makes a prediction in one direction only - states one group will perform significantly better than the other.
• A non-directional hypothesis makes a prediction in one of two directions - it is unsure which of the two groups will perform better.
• A null hypothesis is a prediction about the findings that is tested statistically for significance - states there will be no significant difference between the groups.
• Probability and chance are used to determine the likelihood of an event happening by random occurrence. Psychology uses a probability level of 5%.
• The null hypothesis states that any differences found in the research are due to chance.
• Operationalisation is the process of defining variables and hypotheses precisely to make them measurable. This is stating the exact units/ description of the IV and DV.
• Independent variable (IV) is the variable manipulated by the researcher.
• Dependent variable (DV) is what is measured as a result of the manipulation of the independent variable (IV).
• Internal validity refers to the extent to which the findings are due to the manipulation of the IV rather than other factors, affecting the outcome of the results.
• Directional hypothesis (one-tailed) predicts a difference in one direction, while non-directional hypothesis predicts a difference in one of two directions (two-tailed).
• The aim of a research investigation is the reason for conducting the study. General purpose, not a prediction.
• The null hypothesis predicts that the findings are due to chance rather than changes in the independent variable (IV).
• Operationalisation is the process of avoiding ambiguity and maintaining internal validity by making variables and hypotheses clear and measurable.
• All research must have an aim.
• The aim is s statement about what the researcher wants to investigate.
• It is usually kept quite broad and is written using the format:

  'The aim of the research is to investigate...'
• The thing (variable) the experimenter manipulates or changes is known as the independent variable.
• The thing(variable) the experimenter measures the effect of(the results) is known as the dependent variable.
• Experimental method is unique in that it is the only research method in psychology that tests cause and effect.
• To ensure the cause and effect is established it is important that we identify exactly how the IV and the DV will be measured.
• Known as operationalising the variables.
• Enables other psychologists to replicate your research and is essential in establishing reliability.
• An example of operationalising is:

  Babies will show a preference for different types of patterns.

  Operationalised IV- Stripey, Plaid and Spotty Patterns

  Operationalised DV- The amount of time spent touching the spotty, plaid or stripey patterns.
• Hypotheses are statements about the prediction of the results.
• There are some general rules when formulating them.
• Typically these are:

  • are written in the future tense
  • include both conditions of the IV.
  • include the DV.
• Four hypotheses are:

  Null Hypotheses

  Alternative Hypotheses

  One tailed (Directional) Hypotheses

  Two Tailed(Non-Directional) Hypotheses
• Null hypotheses:

  These predict that no difference will be found in the results between the conditions.
• Typically, these are written as 'There will be no difference...'
• Alternative Hypotheses:

  These predict that there will be significant difference in the results between two conditions.
• Directional and non-directional hypotheses are the options for an alternative hypothesis.
• One Tailed Hypotheses:

  These state the specific direction the researcher expects the results to move in, e.g. higher, lower, more, less.
• Two Tailed Hypotheses:

  These state that a difference will be found between the conditions of the IV but do not state which direction the difference will be in.
• All research has an alternative hypothesis( either one tailed or two tailed) and a corresponding null hypothesis.
• For example,

  Boys will show more physical aggression than girls.

  Alternative one tailed.

  There will be no difference in the physical aggression shown by boys and girls.
• One Tailed- Existing research

  Two Tailed- No existing research