research methods Flashcards
what is the first stage of planning an experiment?
aim
what is involved in the aim?
- focus of our research to produce an aim
- aims are developed from theories and based on many more hours of research
- aims are general statements that describe the purpose of an investigation
- example of an aim would be something like:
to investigate whether drinking energy drinks makes people more talkative
what is the second stage of an experiment?
hypothesis
what is a hypothesis?
a hypothesis is a statement made at the beginning of an experiment to clearly state the relationship between variables
what is 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”, “less”, “higher” or “lower”
what a non directional hypothesis?
- the researcher simply states that there will be a difference between conditions or groups of people but the nature of the difference is not specified
-e.g people who drink HELL differ in terms of talkativeness compared with people who don’t drink hell
when is a directional hypothesis used?
when the findings of previous research suggests a particular outcome
when is a non directional hypothesis used?
when there is no previous research, or findings from previous studies are contradictory, they will use a non-directional hypothesis instead
what is the IV?
what in the experiment that the researcher manipulates
what is the DV?
what in the experiment that the researcher records and measures the effect of this change on the dependent variable
what is the levels of IV ?
If an experiment compares an experimental treatment with a control treatment, then the independent variable (type of treatment) has two levels: experimental and control.
what is operationalisation of variables?
- many aspects of human behaviour that psychologists study can be complex in construct e.g cognitive thinking, social behaviour
- one of the main tasks for the researcher is to ensure that the variables being investigated are as clear and measurable as possible
what does statistical testing do?
a statistical test tells us which hypothesis is “true” and thus whether we should accept the null hypothesis or accept the alternative hypothesis
what is the first stage of statistical testing?
researchers begin by creating either a directional or non directional hypothesis
either is referred to as an alternative hypothesis (H1 for short) because it is alternative to the null hypothesis ( or H0)
what can the researcher do if the levels meet?
the researcher can reject the null hypothesis and accept the alternative hypothesis
what is the usual level of significance?
- 0.05 ( or 5%)
- this is properly written as p <_ 0.05
- this means the probability that the observed effect (the result) occurred when there is no effect in the population is equal to, or less than, 5%
when is the usual level of significance dropped ?
0.05 is the accepted level, but if there is a greater risk to human cost, it is reduced to 0.01
what happens once a statistical test has been completed?
- the result is a number, the calculated value (sometimes referred to as the observed value)
how do we check for statistical significance?
the calculated value must be compared with a critical value, the calculated value must be greater than or equal to, or less than or equal to
what is the criteria for statistical tables?
- one - tailed or two - tailed test? directional = one tailed , non directional = two tailed
- the number of participants in the study - usually appears as N. For some tests, degrees of freedom are calculated instead
- the level of significance- 0.05 is the standard level in psychological research. In some studies, 0.01 might be used if there is a greater risk to human cost e.g drug trials
what is the sign test and what is the criteria that must be met?
- a simple statistical test to calculate whether a difference found is significant
three criteria must be met:
-we need to be looking for a difference, rather than an association
- we need to have a repeated measures design
- we need data that is organised into categories, or nominal data
-data must be converted before the sign test is completed
what are the stages of the sign test?
- Calculate the + and – sign for the given distribution. Put a + sign for a value greater than the mean value, and put a – sign for a value less than the mean value. Put 0 as the value is equal to the mean value; pairs with 0 as the mean value are considered ties.
- Denote the total number of signs by ‘n’ (ignore the zero sign) and the number of less frequent signs by ‘S.’
- Obtain the critical value (K) at .05 of the significance level
why do we use a statistical test?
- they work out the probability of whether a particular set of data could have occurred by chance
- we may have found a difference between our two samples but
- we want to know if this differences is big enough to be of significance
- this helps us to know if we can reject the null hypothesis
what are the 3 D’s ?
- levels of Data e.g nominal, ordinal or interval
- Design e.g related (repeated) or unrelated (independent)
- Test of Difference or correlation ( difference shows more specific results, correlation is a general relationship)
what is nominal data
- named categories
-no true mathematical values
-basic form of data
-presented in bar charges ( do not touch as data is separate)
what are some examples of nominal data
male/ female
tall / small
happy/ upset
what is ordinal data?
- ordered data
- understand relationships between places
- no true mathematical values
- typically scales
-represented in bar charts
what is an example of ordinal data ?
place in a race (1st, 2nd, 3rd) (ranked data)
what is interval data?
- true mathematical values
-relationships between data - can go below 0
what is an example of interval data?
- temperature
- gap between numbers (-2 → -4 is the same as 34 → 36)