A2 RESEARCH METHODS- inferential stats- measures of central tendancy/measures of dispersion

Question 1

what does inferential stats allow?

Answer 1

psychologists to draw conclusions based on probability that a particular pattern of results could have arisen by chance

Question 2

what if unlikely that results occurred by chance?

Answer 2

described as significant

Question 3

in most research what do psychologists say?

Answer 3

if results are sig if probability occurred by chance is less than 0.05

Question 4

how is p less than 0.05 written?

Answer 4

p,0.05

Question 5

what is it meant in other words?

Answer 5

risk that results occurred by chances is less than 0.05 / 5% so we can be more than 95% sure that they were due to effect of iv and dv

Question 6

if psychologists want to be more significant what do they do?

Answer 6

p

Question 7

what do inferential tests determine?

Answer 7

likelihood that results due to chance.

Question 8

what do they produce?

Answer 8

observed value

Question 9

what must an observed value be compared to?

Answer 9

critical value which comes from table

Question 10

in spearmans rho and chi square tests the observed value must be?

Answer 10

must be greater than critical to be sig

Question 11

in mann whitney and wilcoxon tests the observed value must be?

Answer 11

less than critical value for result to be sig

Question 12

what are the two types of errors?

Answer 12

type 1 & type 2

Question 13

what are type 1 errors?

Answer 13

rejecting a null hypothesis that is true and accepting a experimental hyp that is not true. happens when level of signifcance too high e.g 10%

Question 14

what are type 2 errors?

Answer 14

accepting null when not true and rejecting experimental that is true -happens when sig too low e.g 1%

Question 15

what are the types of levels of measurements?

Answer 15

nominal, ordinal, interval

Question 16

what is nominal data?

Answer 16

data in separate categories such as grouped into tall,medium,short. names of categories are simply labels

Question 17

what is ordinal data?

Answer 17

data ordered/ranked but gap btw each item not the same e.g rating how happy u are on scale of 5

Question 18

what is interval data?

Answer 18

data measured using specific units of measurement which are equally spaced apart such as measuring height in cm

Question 19

what are the types of inferential tests?

Answer 19

spearmans rho,
chi square
mann whitney u test
wilcoxon test

Question 20

when would you use spearmans rho?

Answer 20

testing for correlation, data is ordinal interval or ratio, there are no or few tied ranks

Question 21

when would you use chi square?

Answer 21

data is nominal, no other test suitable!

Question 22

when would you use mann whitney?

Answer 22

testing for difference, indepdant groups design, data ordinal interval or rational

Question 23

when would you use wilcoxon?

Answer 23

testing for difference, there is repeated measures design, data is ordinal interval or ratio

Question 24

what are the measures of central tendancy?

Answer 24

mean
median
mode

Question 25

what is mean?

Answer 25

found by adding up all values and dividing by values

Question 26

advantages of mean?

Answer 26

makes use of all values in data set

Question 27

disadvantages of mean?

Answer 27

can be misrepresentative if there are extreme values

Question 28

what is median?

Answer 28

middle value of ordered value could do number of scores + 1 / 2 if there are even number of scores then middle = 10 + 1 /2

Question 29

advantages of median?

Answer 29

not affected by extreme values

Question 30

disadvantages of median?

Answer 30

not as sensitive as mean as not all values reflected

Question 31

what is mode?

Answer 31

most common value- remeber may be more than one mode should report all

Question 32

advantages of mode?

Answer 32

easy to calculate provides direct info

Question 33

disadvantages of mode?

Answer 33

not useful when there are several modes

Question 34

what are the measures of dispersion?

Answer 34

range

standard deviation

Question 35

what is range?

Answer 35

difference btw highest and lowest score in a data set

Question 36

advantage of range?

Answer 36

easy to calculate and provides direct info

Question 37

disadvantage of range?

Answer 37

affected by extreme values doesnt consider number of values in data set

Question 38

what s standard deviation?

Answer 38

assesses the spread of data around mean to show the amount of variation in a data set. a greater standard devation means there is greater variation in data set

Question 39

advantage of standard deviation?

Answer 39

more precise measure of dispersion as all values taken into account

Question 40

disadvantage of standard deviation?

Answer 40

may hide some characteristics of the data,eg extreme values