PSYCH10004 research module

population

everyone of interest to a research question

sample

a group of people taken from the population to participate in a study

how are inferences made about populations in psychological research?

by using evidence gathered from measuring samples

what features are used to describe distributions of data?

frequency and magnitude

histograms

the higher the bar on a histogram the more people have received that particular score

distribution of sample means

made up of the sample means of from all of the random samples of a certain size that could possibly be obtained from a population

central limit theorem

mean of the distribution of sample of sample means is the same as the population mean

central limit theorem tells us that if a samples large enough

the distribution of sample means will be normal

how can we decide if a sample is typical or extreme

by comparing the sample mean with a distribution of sample means

law of large numbers

larger samples increase the probability that the sample mean is close to the population mean

null hypothesis

hypothesis of no effect

null hypothesis significance testing

1. propose a null hypothesis that a population parameter (mean) has a particular value

2. proceed assuming the null hypothesis is true

3. determine the probability of the sample mean occurring if the null hypothesis is true

4. if the probability of the sample mean occurring is small, reject null hypothesis. if the probability is large, do not reject null hypothesis

experimental hypothesis

a hypothesis of effect

type 1 error in hypothesis testing

calculating a larger standard error than needed