4.2.3.3 INTRODUCTION TO STATISTICAL TESTING

Question 1

what is the sign test?

Answer 1

• a method used in inferential statistics to determine whether or not an observed result (from an experiment) is significant or not
• is a non-parametric test which means that there’s no assumption that the data will follow a normal distribution
• known as the sign test as it’s based on the number of play or minus signs present in the data after the calculations have taken place

Question 2

what criteria determine the use of the sign test?

Answer 2

• investigating a difference
• repeated measures design
• nominal data
• is the hypothesis directional or non-directional
  -> will determine which critical value to apply to the data

Question 3

what are 2 advantages of using the sign test?

Answer 3

1) is a simple test which is easy to carry out

2) can be applied across a range of situations where a normal distribution cannot be assumed

Question 4

what are 2 disadvantages of using the sign test?

Answer 4

1) nominal data us the least powerful type of data which means that the sign test can sometimes be unreliable

2) may not be suitable for use with small samples or when the median has been used as the measure of central tendency

Question 5

how do you calculate the S value?

Answer 5

• work out the difference between condition 1 and condition 2
• state whether this is a - or + value
• count up how many -ve values you got and how many +ve value you got
• whichever has the lowest amount is the S value
• the S value is always the lower value