Scientific Processes Flashcards
What is an aim ?
An aim identifies the purpose of the investigation
What is a hypothesis?
- A hypothesis is a testable prediction about the variables in a study.
- The hypothesis should always contain the independent variable (IV) and the dependent variable (DV).
- A hypothesis can be directional (one-tailed) or non-directional (two-tailed).
What are two types of hypothesis?
1.Research hypothesis
2. Null hypothesis
What is a research hypothesis?
predicts a statistically significant effect of an IV on a DV (i.e. an experiment), or a significant relationship between variables (i.e. a correlation study), e.g.
In an experiment: “Athletes who have a training partner are likely to score higher on a questionnaire measuring motivation levels than athletes who train alone.”
In a correlation study: ‘There will be a significant positive correlation between athletes’ motivation questionnaire scores and the number of partners athletes train with.”
What is a directional (one -tailed) ?
A directional hypothesis is a one-tailed hypothesis that states the direction of the difference or relationship (e.g. boys are more helpful than girls).
What is a non-directional ( two - tailed )
A non-directional hypothesis is a two-tailed hypothesis that does not predict the direction of the difference or relationship (e.g. girls and boys are different in terms of helpfulness).
What is null hypothesis?
This predicts that a statistically significant effect or relationship will not be found, e.g.
In an experiment: “There will be no significant difference in motivation questionnaire scores between athletes who train with and without a training partner.”
In a correlation study: “There will be no significant relationship between motivation questionnaire scores and the number of partners athletes train with.”
What is a population?
A population is an entire group with specified characteristics. The target group/population is the desired population subgroup to be studied, and therefore want research findings to generalise to.
What are representative sample?
A representative sample is a subset of the target group with a similar distribution of relevant characteristics, in turn allowing us to generalise from the sample to the target group with some justification.
What are random sampling ?
This method gives every member of the target group an equal chance of being selected for the sample (e.g. by assigning a number to each member, and then selecting from the pool at using a random number generator).
Strengths of random sampling ?
It is widely accepted that since each member has the same probability of being selected, there is a reasonable chance of achieving a representative sample.
Weakness of random sampling
- Small minority groups within your target group may distort results, even with a random sampling technique.
- It can be impractical (or not possible) to use a completely random technique, e.g. the target group may be too large to assign numbers to.
What is systematic sampling ?
A systematic method is chosen for selecting from a target group, e.g. every fourth person in a list could be used in the sample. It differs from random sampling in that it does not give an equal chance of selection to each individual in the target group.
Strengths of systematic sampling ?
Assuming the list order has been randomised, this method offers an unbiased chance of gaining a representative sample.
Weakness of systematic sampling ?
If the list has been assembled in any other way, bias may be present. For example if every fourth person in the list was male, you would have only males in your sample.
What is stratified sampling ?
- Here the sampler divides or ‘stratifies’ the target group into sections, each showing a key characteristic which should be present in the final sample.
- Then each of those sections is sampled individually.
- The sample thus created should contain members from each key characteristic in a proportion representative of the target population.
Advantages of stratified sampling ?
It avoids the problem of misrepresentation sometimes caused by purely random sampling.
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.
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.
Strengths of opportunity sampling ?
- This method is easy and inexpensive to carry out.
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).
Volunteer sampling
Here the sample consists of people who have volunteered to be in the study.
Strengths of volunteer sampling ?
This often achieves a large sample size through reaching a wide audience, for example with online advertisements.
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.
