Research Methods Modules Flashcards
difference
is one group of people different to another in some way?
association
is one construct related to another?
prediction
does one construct influence another?
goal of psychological research
to make inferences about a population (inferring that what is typical for sample is typical for population)
population
everyone of interest to a research question
distributions of data can be described according to their
central tendency (eg. Mean) and variability (eg. Standard deviation)
the normal distribution
majority of observations in the middle, observations reduce in frequency towards the tails, the distribution is symmetrical
in a normal distribution, most observations are closed to m; these scores occur more
frequently; typical
the 2s Rule of Thumb
in a distribution with a normal shape, 95% of scores fall within approximately 2 standard deviations from the mean. These scores are typical
typical scores
are expected and occur frequently
extreme scores
are not expected and occur infrequently
distribution of sample means
made up of the sample means from all of the random samples of a certain size (n) that could possibly be obtained from a population
Central Limit Theorem tell us
the precise characteristics of a distribution of sample means for samples of any size (n). The distribution of sample means has equal mean to the population mean, for large sample sizes, the distribution of sample means will be normal, details of standard error, as sample size increases, standard error decreases and estimation of population mean becomes more precise
standard error
standard deviation of the distribution of sample means
when sample is large enough, it provides
a reliable estimate of the population mean
z-test standard error formula
standard error = standard deviation of population/(number of people in sample)^1/2
we can use 2s Rule of Thumb to test if our SAMPLE MEAN
is typical or extreme
hypothesis
a statement that predicts that something is going to happen
experimental hypothesis/alternative hypothesis
a statement that predicts an effect (one of difference or association)
null hypothesis
predicts that nothing is happening; a hypothesis of no effect (no difference, no association)
only one of null/experimental hypothesis can be
supported by research data at any one time
null hypothesis statistical notation
H0
experimental hypothesis statistical notation
H1
null hypothesis significance testing
propose a null hypothesis that a population parameter (mean) has a particular value. Proceed assuming the null hypothesis is true. Determine the probability of the sample mean occurring if the null hypothesis is true. If the probability of the sample mean occurring is small, reject the null hypothesis. If the probability is large, do not reject the null hypothesis