statistics

Question 1

what is a census

Answer 1

measures every member of a population

Question 2

advantage of a census

Answer 2

accurate results

Question 3

disadvantage of a census

Answer 3

expensive / testing may destroy the population

Question 4

what is a sampling unit

Answer 4

individuals of a population

Question 5

what is a sampling frame

Answer 5

a list of sampling units

Question 6

what is simple random sampling

Answer 6

same chance of being selected.
random number generator

Question 7

advantage of simple random sampling

Answer 7

bias free

Question 8

disadvantage of simple random sampling

Answer 8

need a sampling frame

Question 9

what is systematic sampling

Answer 9

take every k’th unit. k=pop/sample
pick random number between 1 and k to start

Question 10

advantage of systematic sampling

Answer 10

quick to use

Question 11

disadvantage of systematic sampling

Answer 11

need a sampling frame

Question 12

what is stratified sampling

Answer 12

sample represents the groups (strata) of a population.
sample/population x strata
to find out how many people you need in each group

Question 13

advantage of stratified sampling

Answer 13

reflects population

Question 14

disadvantage of stratified sampling

Answer 14

population must be classified in strata

Question 15

what are strata

Answer 15

groups

Question 16

what is quota sampling

Answer 16

like stratified but strata is filled by interviewer/researcher

Question 17

advantages of quota sampling

Answer 17

no sampling frame

Question 18

disadvantages of quota sampling

Answer 18

non random, potential bias

Question 19

what is opportunity sampling

Answer 19

quota filled by those available at the time

Question 20

advantages of opportunity sampling

Answer 20

easy/cheap

Question 21

disadvantages of opportunity sampling

Answer 21

unlikely to be representative

Question 22

how to calculate the variance

Answer 22

(sum of x^2 / n) - mean ^2
mean of the squares minus the square of the mean

Question 23

go to get from variance to standard deviation

Answer 23

square root variance = standard deviation

Question 24

why are histograms used

Answer 24

for continuous data

Question 25

what to compare on histograms

Answer 25

measure of location and measure of spread

Question 26

what does PMCC mean

Answer 26

product moment correlation coefficient

Question 27

what does PMCC measure

Answer 27

strength and +/- of correlation

Question 28

what is a regressions line

Answer 28

the best line of best fit

Question 29

what is interpolation

Answer 29

estimating inside the data range more reliable

Question 30

what is extrapolation

Answer 30

estimating outside the data range less reliable

Question 31

what is U on venn diagrams

Answer 31

shade all of both

Question 32

what is n on venn diagrams

Answer 32

shade overlap

Question 33

what does B| A mean

Answer 33

probability of B given that A has been picked

Question 34

what is a mutually exclusive event and its properties

Answer 34

the venn diagram does not overlap P(AnB) = 0 P (AUB) = P(A) + P(B)

Question 35

probabilities of independant events on venn diagrams

Answer 35

P(AnB)= P(A) x P(B) P(A|B) = P(A)

Question 36

conditional probability formula P(B|A) =

Answer 36

P(AnB)/P(A)

Question 37

Addition law for probability P(AUB) =

Answer 37

P(A) + P(B) - P(AnB)

Question 38

what is discrete uniform distributions

Answer 38

probabilities of all outcomes are equal

Question 39

Binomial distribution notation

Answer 39

X~B(n,p) X is distributed binomials n = number of trials p = probability of success

Question 40

when to use a binomial distribution

Answer 40

F - fixed number of trials F - fixed probability of success I - independent T - Two outcomes

Question 41

cumulative probability of P(X<5)

Answer 41

P(X<_ 4)

Question 42

cumulative probability of P(X>3)

Answer 42

1 - P(X<_3)

Question 43

cumulative probability of P(6

Answer 43

P(X<_10) - P(X<_6)

Question 44

what is normal distribution

Answer 44

used for continuous random variables

Question 45

normal distribution notation

Answer 45

Y ~ N (mean , variance) y is distributed normally

Question 46

what are the points of inflection on normal distribution

Answer 46

mean + /- standard deviation

Question 47

what is the notation of standard normal distribution

Answer 47

Z~N(0, 1^2)

Question 48

coding Z~ Z=

Answer 48

Y-mean/standard deviation

Question 49

when can you approximate binomial distributions as normal distributions

Answer 49

if N is large if p is approximately 0.5 mean = np variance = np(1-p)

Question 50

if you are approximating binomial as normal you are going from discrete to continuous values so you must change the values of the probability. e.g. P(X>5)

Answer 50

= P(Y> 4.5)

Question 51

what is the null hypothesis

Answer 51

H0 what we assume to be true

Question 52

what is alternative hypothesis

Answer 52

H1 what would be true if H0 is wrong

Question 53

what is significance level

Answer 53

the given threshold of likeliness

Question 54

what is a one tailed test

Answer 54

H1 : p>k or p

Question 55

what is a two tailed test

Answer 55

when H1 : p does not equal k half significance level for each end

Question 56

for correlation testing what is H0 and H1 compare r with table for more extreme less extreme

Answer 56

H0: r=0 H1= r>0 or r<0 or r is not 0 if more extreme reject H0 is less extreme no evidence to reject H0

Question 57

for binomial testing what is test statistic H1 H0 assume H0 is

Answer 57

test statistic : number of successes observed H0: p=k H1 = p>k p_ value in question) if p< significance level - reject H0 if p> significance level - no evidence to reject H0

Question 58

for normal testing what is sample mean H0 H1 assume H0 is

Answer 58

sample mean ~ N ( mean, variance/n) H0 : mean = k H1: mean > k mean < k or mean is not K assume sample mean ~N ( k, variance/n) find P(sample mean > or < mean of sample taken) if p significance level - no evidence to reject H0