Measures Of Central Tendency And Variability L2

Question 1

What type of data are histograms used with?

Answer 1

Continuous data

Question 2

What is kurtosis?

Answer 2

Kurtosis refers to the height of the slope

Question 3

What does the choice of which measure of central tendency to use come down to?

Answer 3

The scale of measurement of the variable

The type of the frequency distribution

Question 4

What occurs in a bimodal distribution?

Answer 4

The mean and median are the same value but there are 2 modes

Question 5

What is the problem with using the mean for a skewed distribution?

Answer 5

The mean will be misleading due to the skewed data, the median should be used as it’s not affected by extreme scores

Question 6

In a positivity skewed data distribution, reading from left to right, what is the order of the measures of central tendency?
Also what about for a negatively skewed data distribution?

Answer 6

Mode median mean

Mean median mode

Question 7

What type of data is best used with the mode?

Answer 7

Nominal data but the mode can also be used with interval and ratio data

Question 8

What type of data is suitable for the median to be used?

Answer 8

Typically used with ordinal data , not suitable for nominal data

Question 9

What type of data is suitable for use with the mean?

Answer 9

Pointless to use with nominal or ordinal data

Question 10

What does heterogenous and homogenous mean?

Answer 10

Heterogenous refers to high variability

Homogenous refers to low variability

Question 11

Discuss standard deviation and the data with reference to percentages of scores?

Answer 11

68% of scores will fall within plus/minus 1 SD of the mean
95% of scores will fall within plus/minus 2 SD of the mean
99.7% of scores will fall within plus/minus 3 SD of the mean

Question 12

What is the equation for standard error?

Answer 12

Standard deviation / square root of the number of participants

Question 13

When referring to box plots, what is considered a minor outlier?

Answer 13

Those data values between 1.5X and 3X the interquartile range from the upper and lower edges

Question 14

When referring to box plots, what is considered an extreme outlier?

Answer 14

A data value which is more than 3X the IQR from the upper and lower edges

Question 15

What is a Z score, provide the equation.

Answer 15

Z = (X-M)/ SD
Where X is the value, M is the mean.

A z score allows standardisation of different distributions so raw scores can be compared (e.g. Long jump vs triple jump)

Question 16

Discuss typical scores found in Z distributions.

Answer 16

The mean of the data is always 0
The SD always equals 1

Z scores will range from -3 to +3 and larger the score means a further distance away from the mean.