Lecture 4

Question 1

What are the 4 types of variables?

Answer 1

• dichotomous
• ordinal
• categorical
• continuous

Question 2

What are the two pieces of information in every frequency distribution table for any type of variable?

Answer 2

frequency and relative frequency

Question 3

How do you calculate relative frequency (%)?

Answer 3

RF = (frequency / total # of responses) x 100%

Question 4

What two additional pieces of data is calculated for ordinal variables?

Answer 4

cumulative and cumulative relative frequency

Question 5

What are the two types of measurements of continuous variables?

Answer 5

central tendencies and variability

Question 6

What are the three central tendency measurements?

Answer 6

mean, median, and mode

Question 7

What are the four variability measurements?

Answer 7

range, IQR, variance, and standard deviation (SD)

Question 8

If data is missing, is that individual still counted in the total # of persons?

Answer 8

No, only participants who provided a value are accounted for in the denominator

Question 9

What is mean denoted as?

Answer 9

x-bar

Question 10

What are the advantages to median?

Answer 10

• not impacted by outliers
• good index of what is “typical” if distribution is skewed
• some categorical data can have the median applied
• good for ordinal data

Question 11

What is the main disadvantage of median?

Answer 11

does NOT take the data values themself into account (only a position indicator)

Question 12

What are the advantages of mode?

Answer 12

• can be applied to any variable type (even nominal)
• reflects and actual value from the data (easy to understand)
• useful when there are multiple common values

Question 13

What are the disadvantages to mode?

Answer 13

• ignores majority of other info regrading distribution
• tends to vary between samples
• some samples do not have a mode

Question 14

In a normal distribution, where are all the central tendencies found?

Answer 14

in the center of the bell-curve

Question 15

In skewed distributions, where are the central tendencies found?

Answer 15

positive skew (tail to right)- mode > median > mean
negative skew (tail to left) - mean < median < mode
- in both the mean is what is off centered towards the tail end

Question 16

Where are the outliers found in skewed curves?

Answer 16

on the lower tail ends

Question 17

What are the two types of variability?

Answer 17

heterogeneous (high variability)
homogeneous (low variability)

Question 18

What percentage of the variation does range represent?

Answer 18

100%

Question 19

What is the advantage to range?

Answer 19

it’s easily understood

Question 20

What are the disadvantages to range?

Answer 20

• only dependent on 2 scores (not all info taken into account)
• sensitive to outliers
• tends to vary between samples
• influenced by sample size

Question 21

What percentage of the variation does the IQR represent?

Answer 21

50%

Question 22

What are the advantages to the IQR?

Answer 22

• reduced influence of outliers (only the middle 50% is looked at)
• uses more information than range
• helpful for evaluating/identifying outliers
• appropriate for ordinal measures

Question 23

What are the disadvantages of the IQR?

Answer 23

• not easy to compute
• not well understood
• doesn’t take all values into account

Question 24

What is deviance?

Answer 24

the spread of the scores (how different each score is from the center of a distribution)

Question 25

What is the deviance equation?

Answer 25

deviance = xᵢ - X̄

Question 26

What is variance?

Answer 26

indicates the total dispersion of scores from the MEAN

Question 27

What is the variance equation?

Answer 27

variance = (sum of (devience)^2) / N - 1

Question 28

What needs to be done to the variance in order to obtain the standard deviation?

Answer 28

square root the value

Question 29

What is the interpretation of the standard deviation?

Answer 29

• high result = values are FAR off from the mean
• low results = values are not that far off (close to the mean)

Question 30

In a normal distribution, past what point are value considered outliers?

Answer 30

anything beyond +/- 1.96 standard deviations

Question 31

When outliers are NOT present, which central tendency and variability values are appropriate?

Answer 31

sample mean and the standard deviation

Question 32

When outliers ARE present, which central tendency and variability values are appropriate?

Answer 32

median and interquartile range

Question 33

What is the equation for calculating the upper and lower limits to determine mild outliers?

Answer 33

lower limit = Q1 - (1.5IQR)
upper limit = Q3 - (1.5IQR)

Question 34

What is the equation for calculating the upper and lower limits to determine extreme outliers?

Answer 34

lower limit = Q1 - (3IQR)
upper limit = Q3 - (3IQR)

Question 35

What type of graph is used to represent dichotomous or categorical variables?

Answer 35

bar charts (frequencies and relative frequencies)

Question 36

What type of graph is used to represent ordinal variables?

Answer 36

histograms (frequencies, relative frequencies, cumulative frequencies, and cumulative relative frequencies)

Question 37

What type of graph is used to represent continuous variables?

Answer 37

boxplot (central tendencies and variabilities/ranges)