research methods- statistical testing: the sign test

Question 1

what is significance?

Answer 1

difference/association between two sets of data is greater than would occur by chance

Question 2

what is probability?

Answer 2

p is about likelihood - how likely it is that a certain event will happen if the null hypothesis were true

Question 3

what is the accepted level of probability in psychology?

Answer 3

0.05 (significance level of 5%)

Question 4

what is the significance of the accepted probability level in psychology?

Answer 4

this is the level at which a researcher decides to accept/reject the null hypothesis

Question 5

why do psychologists use phrases such as ‘this suggests’ rather than ‘this proves’?

Answer 5

even though they may find statistically significant differences/relationships within data, they can never find statistical certainties

Question 6

what does the researcher use a statistical test for?

Answer 6

to produce a calculated value

Question 7

what is the calculated value compared with and why?

Answer 7

calculate value compared with a critical value to decide if the result is significant or not

Question 8

where are the critical values found?

Answer 8

in a table of critical values

Question 9

what do you need to know to find the critical value?

Answer 9

-significance level (usually 0.05/5%)
-no. of p’s in investigation (𝑁 value) or the degrees of freedom (𝑑ƒ)
-whether hypothesis is direction (one-tailed) or non-directional (two-tailed)

Question 10

what are the conditions of use for the sign test?

Answer 10

-difference in scores must be between related items, e.g. same participant used twice (repeated measures)
-can be used w nominal data (or better)

Question 11

how is the s value calculated?

Answer 11

1. work out difference whether its increased or decreased
2. add up no. of + and no of -
3. p’s who achieved same score in both conditions disregards an deducted from 𝑁 value
4. S value is the total of the less frequent sign