4. Normal distributions and z-scores

Question 1

What does the normal curve show? (Methods1 normal distributions)

Answer 1

Frequency distribution in real life

Question 2

What are the five properties of a normal distribution? (Methods1 normal distributions)

Answer 2

• Bell shaped
• Symmetrical around the mean
• Answers for the mean, median and mode that are the same
• Area under the curve is directly proportional to the relative frequency
• The SD cuts off a constant proportion of the distribution of scores

Question 3

If you know that scores are normally distributed and the SD, what can you work out? (Methods1 normal distributions)

Answer 3

Which upper and lower limits the scores fall

Question 4

What are z-scores? (Methods1 normal distributions)

Answer 4

Standard scores

Question 5

What does a z-score show? (Methods1 normal distributions)

Answer 5

The position of the raw score in relation to the mean of the distribution, using the SD as a unit of measure

Question 6

What is the equation for a z-score? (Methods1 normal distributions)

Answer 6

Z = (raw score - mean) / SD

Question 7

What does using z-scores allow us to do? (Methods1 normal distributions)

Answer 7

1) Compare distributions using different scales

2) Determine the relationship between one score and the rest of the scores