research methods

what is an EV compared to a confound

an EV is an uncontrolled factor that affects the DV, the confound is an extraneous variable that varies systematically with the IV to affect the DV

what are the categorical data types

nominal - categorical data with no hierarchical order

ordinal has an order

what are the types of numerical data

interval which is scalar, continuous and has no meaningful 0 whereas ratio does

what are descriptive statistics

give an overall view of data patterns without having to use all the raw data

what is a Z score

a standardised score that is used for comparing a data point to a mean, good for comparison between ppts or conditions

why do we need normal distribution

to be able to predict the population mean from the sample mean and therfore form generalisable conclusions

what are confidence intervals

they show the spread of data and we can be sure the mean of the population is likely in the middle 95%

what is the idea behind sampling error

that ideally we want to get the mean of the overall whole target population but due to practical reasons we cant so instead we have to take a sample from that population of interest.

the sampling error is the difference between the sample mean and the target pop. mean as inevitably they wont be the same

how to reduce sampling error

get an average mean from multiple samples

use larger samples as they are more likely to be better representations of the whole population

describe type 1 and type 2 errors

type 1 (false positive) = saying that the IV has an affect on the DV when actually it doesnt

type 2 (false negative) = saying the IV doesnt impact DV when it actually does

why do we need hypothesis testing

to see whether, if it actually happened that the IV had no affect on DV, so the null hypothesis was true, how likely is it that you get the same results (type 1 error)

what is the alpha level

the threshold for significance at 0.05, if p value is below this then it is significant

it is saying there is a less than 5% chance that the results were found due to chance and not truly the IV affecting DV.