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Question 1

types of variables

Answer 1

categorical ->describes categories
qualitative-> describes magnitude

discrete-> counted
continous -> measured

Question 2

level of measurement

Answer 2

nom numeric

• nominal: describe categories
• ordinal: describe differences but not to which degree

numeric:

• interval: freely chosen 0 point, describe differences and to what degree
• ratio: fixed 0 point, differences, degree, ratios

Question 3

frequency distribution

Answer 3

nominal scaled

metric scaled: how often a value k is not exceeded

Question 4

measurement of central tendency

Answer 4

mean : average

median: divides set into two halfs
mode: the value that occurs most frequently

Question 5

measurment of dispursion

Answer 5

deviation: how observation differs from mean
variance
standard deviation: typical distance from mean
range: distance between largest and smallest observation

Question 6

bivariate frequency distributions

Answer 6

describe observed frequencies of two variables at a time and their relationship

contingency table:
-describe joint distribution of variables

Question 7

correlation and coveriance

Answer 7

coveriance shows positive association between variables

correlation shows direction if association (-1-1)

spearman rank correlation coefficient if at least on ordinal

Question 8

methods of estimation

Answer 8

ordinary leadt square regression

• difference between observed and estimated value is residual
• OLS shows line with minimum squared distances

Question 9

probability theory

Answer 9

value between 0 and 1 describing the possibility and event will occur

probability distribution:
function that relates value to its probability (e.g binomial how often occurs head when thrown 6 times)

Question 10

probability distribution of continuous random variables

Answer 10

with increasing n it becomes a binomial distribtuon and when n approaches infinity this becomes a normal distribution

no talk about the probability being in a intervall

Question 11

sampling distribution

Answer 11

how close the sample mean is to population mean

central limit theorem
-sampling distribution can be approximated with normal distribution with larger sample size

Question 12

confidence interval

Answer 12

the interval of which you are confident that it will contain the population mean

Question 13

hypothesis test use and steps

Answer 13

test if a claim about a population is correct or not

1. assumption
2. hypothesis (null or alternative null)
3. level of significance (allowing max prob of error)
4. test statistics (two tailed - it is or not, one tailed- above or below)
5. p value

Question 14

one sample t test

Answer 14

tests the distance between sample mean and a value in nr of standard errors

Question 15

independent samples t test

Answer 15

differences of population means

Question 16

chi square test

Answer 16

if variables are independent

with two caregorical variabls

Question 17

pearson correlation

Answer 17

if there is no correlation in the population

with quantitatice variables