3.2.3.2 .1 - Scientific Processes Flashcards
What is an aim ?
- Aims are general statements that describe the purpose of an investigation
- E.g To investigate whether energy drinks make people more talkative
What is an hypotheses ?
- it comes after an aim
- A hypothesis is a statement that is made at the start of a study and clearly describes the relationship between variables as stated by the theory.
What can a hypothesis be ?
-Hypotheses can be directional or non-directional.
In a directional hypothesis the researcher makes clear the sort of difference that is anticipated between two conditions or two groups of people. For this reason, directional hypotheses include words like more or less, higher or lower, faster or slower, etc.
A non-directional hypothesis simply states that there is a difference between conditions or groups of people but, unlike in a directional hypothesis, the nature of the difference is not specified.
What is random sampling ?
Random sample
A random sample is a sophisticated form of sampling in which all members of the target population have an equal chance of being selected.
The first step in selecting a random sample is to obtain a complete list of all members of the target population. Second, all of the names on the list are assigned a number. Finally, the actual sample is selected through the use of some lottery method (a computer/phone randomiser or picking numbers from a hat).
What is a strength of random sampling ?
Strength - potentially unbiased , this means confounding or extraneous variables should be equally divided between the different groups enhancing internal validity.
What is weakness of random sampling ?
- Can end with an unrepresentative sample
- ppts may refuse to take part - all
- time consuming
- difficult to conduct
What is systematic sampling ?
- Systematic sampling is a sampling technique that uses a predetermined system to select the participants from a target group. For example, every fourth person in a list could be used in the sample.
What is a strength of systematic sampling ?
- ## Objective method - researcher has no control over who is chosen (randomly selected)
What are weakness of systematic sampling ?
- time consuming
- some ppts wouldnt want to take part
What is stratified sample ?
- Stratified sampling is a sampling technique where the researcher divides or ‘stratifies’ the target group into sections, each representing a key group (or characteristic) that should be present in the final sample.
What is a strength of stratified sample ?
- reduced sampling bias, better generalizability, and better representation of the population.
What are weakness of stratified sampling ?
- It takes more time and resources to plan.
Care must be taken to ensure each key characteristic present in the population is selected across strata, otherwise this will design a biased sample.
What is opportunity sampling ?
- Participants who are both accessible and willing to take part are targeted, e.g. employees from a conveniently located employer near the laboratory could be selected for the sample group.
What is opportunity sampling ?
Participants who are both accessible and willing to take part are targeted, e.g. employees from a conveniently located employer near the laboratory could be selected for the sample group.
What is a strength of opportunity sampling ?
This method is easy and inexpensive to carry out.
What is the weakness of opportunity sampling ?
- The consequent sample may not be representative as it could be subject to bias (e.g. the conveniently located employer may undertake a selection process for job applicants, making it likely that employees possess certain similar characteristics that are unrepresentative of the wider target group).
What is volunteer sampling ?
- Here the sample consists of people who have volunteered to be in the study.
What is the strength of volunteer sampling ?
- This often achieves a large sample size through reaching a wide audience, for example with online advertisements.
What is a weakness of volunteer sampling ?
- Those who respond to the call for volunteers may all display similar characteristics (such as being more trusting or cooperative than those who did not apply) thus increasing the chances of yielding an unrepresentative sample.
What is a pilot study ?
- Pilot studies are small, trial versions of proposed studies to test their effectiveness and make improvements. They are helpful in identifying potential issues early, which can then be rectified before committing to the length and expense of a full investigation
What are aims of a pilot study ?
- They ensure that the design and material researchers have selected are appropriate for their aims and also use it to help eliminate and control for evs
- This will increases the chances of conducting reliable and valid research therefore allowing strong conclusions from the results.
What is repeated measures ?
- Repeated Measures design is an experimental design where the same participants participate in each independent variable condition. This means that each experiment condition includes the same group of participants.
What is strength of repeated measures ?
- As the same participants are used in each condition, participant variables (i.e., individual differences) are reduced.
What is weakness of repeated measures ?
There may be order effects. Order effects refer to the order of the conditions affecting the participants’ behavior. Performance in the second condition may be better because the participants know what to do (i.e., practice effect). Or their performance might be worse in the second condition because they are tired (i.e., fatigue effect). This limitation can be controlled using counterbalancing.
What is independent groups design ?
- The independent groups design is an experimental design whereby two groups are exposed to different experimental conditions. Usually half of the participants are assigned to the experimental group where they are exposed to a condition where the independent variable is manipulated.
What are strengths of independent groups design ?
- One advantage of using this design is that there are no order effects which affect the outcomes of the experiment.
- These happen when participants take part in both conditions of the experiment, and their performance differs across conditions as a result.
- For example, the practice at doing a memory task felt after the first condition could lead to better performance on the second memory task, irrespective of the manipulation of the independent variable.
What are the weaknesses of independent groups design ?
- One disadvantage of this design is differences between the experimental and control groups may be due to individual differences between participants., rather than the effect of the independent variable. - For example, due to chance, one group may have a better working memory than the other, and when given a memory task, that group will perform better, regardless of the independent variable manipulation, due to pre-disposed advantage. This could be mitigated with random sampling of participants.
What is matched pairs ?
- Matched pairs design is an experimental design where pairs of participants are matched in terms of key variables, such as age and IQ. One member of each pair is then placed into the experimental group and the other member into the control group.
What are some strengths of matched pairs ?
- Strengths
- Order effects will not be observed as participants only take part in one condition.
- The tailored participant-matching process reduces the risk of participant variables (individual differences) from affecting results between conditions.
What are some weaknesses of matched pairs ?
Weaknesses
Different participants need to be recruited for each condition, which is difficult and expensive.
Matching is a more complex process, and it will always be very difficult to match participants identically.