Problem 2

Question 1

label

Answer 1

= a specific variable used in some data sets to distinguish the different cases

Question 2

variable

Answer 2

= a characteristic of a case

- different cases can have different values of variables

Question 3

categorical variable

Answer 3

= places a case into one of several groups/ categories

• description of categories
• -> numbers that have no numerical value

Question 4

categorical nominal

Answer 4

= equal categories (e.g. gender (male/ female))

• -> `naming´
• special case: dichotomous (only two categories)

Question 5

categorical ordinal

Answer 5

= ordered categories (e.g. education level (low/ average/ high)
–> òrdering´

Question 6

quantitative variable

Answer 6

= takes numerical values for which arithmetic operations such as adding and averaging make sense

Question 7

quantitative interval

Answer 7

= meaningful numbers (e.g. IQ 50-150)

• because distance between consecutive units is always equally (in principle)
• -> `distance´
• numbers as we know them, whit the same intervals (between them)

Question 8

quantitative ratio

Answer 8

= an interval variable within an absolute zero point (e.g. age)

• distinguishing ratio from interval isn’t crucially important
• -> `rate´

Question 9

case

Answer 9

= an object that is described by the data

Question 10

exam a distribution

Answer 10

= look for overall pattern like the shape, the spread, the center
–> if distribution is not symmetric, it’s tighter right skewed (positive) or left skewed (negative

Question 11

5-number summary

1. interquartal range (IQR)
2. identify possible outliers (1.5xIQR rule)

Answer 11

asked for:

minimum, maximum; median; Q1, Q3
–> used to make a boxplot

1. = distance between Q1 and Q2 (IQR = Q3 - Q1)
2. = every value that is not in the rage of Q1-1.5xIQR and Q3-1.5xIQR is an outlier

Question 12

measures of centre:

1. mode
2. median
3. (arithmetic) mean

Answer 12

1. = value with highest frequency
   - -> as measure of centre not very informative; useful to see existence of subgroups
2. = value for which it holds 50% for all scores above it and 50% below (middle value)
   - -> spot of median = n+1/2
3. centre of gravity of a distribution (average value)
   - -> X= sum of xi /n

Question 13

1. z-scores

2. standard deviation

Answer 13

1. = in order to compare different distributions with each other & have a linked component 
z = x-x̄/Sx

2. = standard Abweichung (how much the data differs from the mean value)

Question 14

1. descriptive statistics

2. inferential statistics

Answer 14

1. = summary description of data by means of tables, graphs and characteristic measures
2. = conclusions about population based on limited number of elements (= sample) from that population