research methods psy2023

Question 1

what should the answers of pearsons correlation coefficient range between

Answer 1

r and -1 -> 1

Question 2

how to work out sum of xy, sum of x and y squared

Answer 2

xy -> sum of the product of each x*y
sum x/y squared -> sum of each x squared individually

Question 3

what is y = a + (b * x) used for

Answer 3

simple linear regression
best values go into these in order to predict later scores

Question 4

relationship between a and b and b1 and b0

Answer 4

a may be b0 and b may be b1
the equation and process is still the same
may be displayed as y= b0 + b1x

Question 5

what are residual values

Answer 5

the difference between an observed and expected value when predicting scores in linear regression
calculate observed-fitted

Question 6

how to predict values in simple linear regression

Answer 6

put back into equation y=a + (b * x)

Question 7

multiple correlation: how to work out
prop of variability in Y explained by x1 (r2)
p of v in y explained by x2 (r2)
p of v in y explained by x1 and x2(r2)

Answer 7

y and x1 = r01 squared
y and x2 = r02 squared
x1 ans x2 = multiple correlation = rsquared equation

Question 8

what do you need to work out do do the equation in multiple correlation

Answer 8

r01, r02, r12 and their squares

Question 9

when is r12 used in multiple correlation

Answer 9

only the equation, it is not proportion of variability in y explained by x1 and x2 together

Question 10

how to work out a, b, sa, and sb in sobel test

Answer 10

a = effect of x on m (dv=m)
b = effect on m on y (dv = y)
sa and sb of the standard errors

Question 11

what do you need to know in sobel before doing the equation

Answer 11

a, b, a squared, b squared
sa, sab, sa squared and sb squared
make sure negatives are removed when squaring minus numbers

Question 12

how to use lookup table in correlation coefficient

Answer 12

degrees of freedom/numbers on left is N

Question 13

how to assess bias

Answer 13

risk -> avoiding systematic error
control
selection, performance, detection bias and reporting bias

Question 14

how do you use literature to support a mediation model

Answer 14

need 3 relationships
predictor -> outcome
predictor -> mediator
mediatory -> outcome

Question 15

types of mediation

Answer 15

full: entirety of association between y and y is explained by m
partial: some of association between x and y explained by m

Question 16

types of probability based sampling

Answer 16

random
stratified random -> stratify into homogenous groups then simple random
cluster -> natural sampling unit is a group (secondary schools)
systematic -> every nth person from a sampling frame (every 10th to enter website)

Question 17

non probability sampling types

Answer 17

convenience
quota sampling - first 20
snowball - referrals
judgement - based on judgement, sample from representative subgroup

Question 18

errors of coverage - sampling

Answer 18

populations of inferences -> who the conclusions are for
target pop - pop of inference - disregarded groups
frame pop - portion of target pop that may be studied
coverage error is the difference between frame populations and population of inference

Question 19

how to reduce coverage error

Answer 19

obtain as complete as sample frame as possible, or be frameless
post stratifying - weight based on population of inference

Question 20

assumptions for regression models

Answer 20

relationships are linear
errors assumed to be independent (random scatter), normally distributed and with common varience (scatter similar to all points with no obvious patterns)

Question 21

how to test significance of linear regression

Answer 21

test null hypothesis
use one sample t test
if a straight line is suitable to model the data
need slope of regression line to be 0

Question 22

what is the meaning of r squared

Answer 22

the proportion of variability in percentage that measures the proportion of the variance in a dependent variable that is explained by the independent variable(s) in a regression model

Question 23

what the the normality tests

Answer 23

kolmogrov-smirnov and shapiro-wilk
need p values to be non-significant to show that there is no evidence for them not to be normally distributed
need normal distribution

Question 24

what are we interested in in mediation

Answer 24

a - whether a direct effect of x on y exists
b - whether indirect effect of x on y via m exits
c - whether an additional effect of x on y exists having allowed for m

Question 25

what is the casual steps method/baron and kenny's method

Answer 25

1. find effect (significance) of X in a simple linear regression on Y 2. find the effect (significance) of X in a simple linear regression on M 3. find the effect (significance) of m in a multiple regression on y with x 4. find the effect (significance) of x in a multiple regression on Y with M

Question 26

meaning of results from causal steps method

Answer 26

1 tells us about a 2+3 tells us about b 4 tells us about c if x is sig in 1 but not 4 it means m mediates the relationship between x and y

Question 27

what is the simple regression equation in formula and spss terms (step one)

Answer 27

y = a + (b * x) dependent variable = unstandardised coefficient b constant + USB variable x * variable x if it is significant x predicts y

Question 28

what is the regression equation for step 2 in spss output

Answer 28

dependent variable (m) = UCB constant + x variable UCB * grade variable

Question 29

multiple regression equation in spss

Answer 29

y = ucb constant + ucb variable x * x + ucb variable m * m

Question 30

issues with causal steps/baron and kennys method

Answer 30

5% cut off not ideal to measure mediation relationships with

Question 31

alternative to causal steps

Answer 31

using indirect effect ie = a * b where a = regression coefficient using x to predict m b = regression coefficient for m when using x and m to predict y use confidence intervals to assess significance

Question 32

what is a confidence interval

Answer 32

range of values that the true values would lie in 95% of the time

Question 33

common limitations

Answer 33

design -> causation, limited sample application data collection -> bias analysis -> power, clear reporting results -> internal or external validity

Question 34

what is moderation for

Answer 34

to show how the association between predictor and outcome can vary depending on another variable association between x and y depends on m

Question 35

difference between mediation and moderation

Answer 35

med -> x affects y, and x affects m which affects y mod- association between x and y differences depending on m

Question 36

how is moderation visualised on a graph

Answer 36

when groups diverge, converger or cross not when parallel

Question 37

how do effect size, varience and sample size affect significant

Answer 37

es- larger the diff between two groups, more likely the samples diff variable - larger varience, less likely to be sig ss - smaller samples more easily weighted

Question 38

how to centre variables moderation

Answer 38

variable - mean of variable

Question 39

how to write moderation equation

Answer 39

same as linear with y = a + (x * variable) + (x * variable) + ( x * variable1 * variable 2)

Question 40

how to know if there is a mediation model

Answer 40

if theres a stronger association between x and y when m is involved = mediation when just x and y is stronger - no mediation and direct effect

Question 41

how to write up mediation model

Answer 41

state association write equation state significant state what it means state r squared and the % of variation that the variable counts for copy for each and then and the end sum up if there's a model or not

Question 42

how to write up moderation

Answer 42

regression equation what variables contribute to to explaining y and their significance say whether the interaction of x and m is significant, and therefore is there a moderation model

Question 43

what to put into intuitive explanations

Answer 43

what results for x and m alone may mean for y

Question 44

how to read spss results for peason's correlation

Answer 44

look at sig. 2 tailed value

Question 45

how to report pearson's correlation

Answer 45

r squared n value significance evidence to reject null? state null