SUPPLEMENTAL MATERIAL (FOR ONLINE SUPPLEMENT)
(Table I weighted data, Tables II-V unweighted data, Tables VI-VIII weighted and unweighted data)
Methodological Details of Principal Compenents Analysis (PCA) and Factor Analysis
For all PCA and factor analysis reported in this paper, Kaiser's Overall Measure of Sampling Adequacy (MSA) was 0.68 or larger (values greater
than 0.5 are considered adequate) indicating that patterns of correlations are relatively compact and factor analysis should yield distinct and
reliable factors. Items were said to load on a given factor if the absolute value of the relevant loading in the rotated pattern matrix was ≥0.40. We
did not use sample weights provided by Knowledge Networks in the factor analysis. When we used the weights in all of the factor analysis
reported here, the resulting factor scores were correlated with the unweighted factor scores at the 0.945 to 1.000 level. Thus, we decided to use
unweighted factors as we felt using weighted factors would lead to “double weighting” respondents in the regression analyses. Alpha factor
analysis, which treats common factor analysis as a psychometric method, finds uncorrelated common factors based on maximizing generalizability
with regard to coefficient alpha (Cronbach’s alpha, see (ref 79) p 44-45). It does not make distribution assumptions and has some computational
advantages over maximum likelihood factor analysis (ref 80).
Table I-S. Cross-tabulation of Actual Evacuation Zone by Perceived Evacuation Zone (n=804) (WEIGHTED to be representative of the
counties sampled)
Perceived Evacuation
Zone
Not in Evacuation Zone
In Evacuation Zone
Don’t Know
Total
Actual Evacuation Zone
Not In Evacuation
In Evacuation
Zone
Zone
25.5%
17.4%
34.3%
3.5%
17.7%
1.4%
77.5%
22.3%
Total
Texas
(n=347)
Florida
(n=457)
37.9%
43.1%
19.1%
100.0%
54.20%
28.40%
17.40%
100.0%
32.8%
46.7%
20.5%
100.0%
Table II-S. Socio-demographics of Sample (n=804) (Unweighted Data)
Characteristic
Mean
Min
Max
Age (Years)
51.7
18
Total Years Residing in Hurricane Vulnerable Area
26.6
Education (Years)
Income (Thousands)
Household Size (Total Number in Household)
Florida
(n=457)
54.1
t-test TX=FL
88
Texas
(n=347)
48.6
0
86
27.8
25.6
1.62
14.5
4
22
14.5
14.6
-0.70
57.8
5
175
60.3
55.9
1.41
2.7
1
11
2.8
2.6
2.30**
-4.58***
Characteristic Summary statistics
% Dummy =1
Florida
(n=457)
42.2%
z-score a TX=FL
0.72
Gender (Male=1; Female=0)
39.6%
Texas
(n=347)
36.0%
Own Residence (Yes=1; No=0)
68.8%
67.4%
69.8%
1.78*
Children in House (Yes=1; No=0)
31.7%
36.3%
28.2%
2.44**
Took Survey In Spanish (Yes=1; No=0)
21.6%
10.7%
30.0%
6.58***
House Type (Single Detached=1; Other=0)
57.3%
66.3%
50.1%
4.46***
*, **, *** significant at the 10%, 5%, or 1% level respectively
a
Z-score from Mann-Whitney U test for two independent samples (absolute value of Z; asymptotic significance).
Table III-S. Cultural Theory – Summary Statistics and Factor Analysis (n=804) (Unweighted Data)
Statement
Mean
Texas
(n=347)
Florida
(n=457)
K-W test
TX=FL
Factor1 Factor2
Individual Egalitari
ist
an
0.83
-0.10
Government regulation of business usually does more harm than good.
3.17
3.23
3.13
2.2
If the government spent less time trying to fix everyone's problems, we'd all be
a lot better off.
The government interferes too much in our everyday lives.
3.20
3.28
3.14
2.1
0.82
-0.18
3.28
3.39
3.20
5.5**
0.80
-0.23
Our government tries to do too many things for too many people. We should
just let people take care of themselves.
People should be allowed to make as much money as they can, even if it means
some make millions while others live in poverty.
The world would be a more peaceful place if its wealth were divided more
equally among nations.
In my ideal society, all basic needs (food, housing, health care, education)
would be guaranteed by the government for everyone.
I support government programs to get rid of poverty.
2.97
3.04
2.91
2.4
0.77
-0.28
3.20
3.23
3.18
0.2
0.49
-0.48
2.92
2.77
3.04
8.5***
-0.13
0.82
2.81
2.73
2.87
2.2
-0.17
0.75
3.49
3.33
3.60
12.4***
-0.29
0.73
Discrimination against minorities is still a very serious problem in our society.
3.47
3.41
3.52
1.4
-0.15
0.69
Variance explained by each rotated factor
33.0%
29.6%
For all individual items the response scale was: Strongly Disagree=1; Disagree=2; Neither Agree nor Disagree=3; Agree=4; Strongly Agree=5
(numerical labels were not provided with the response scale).
K-W – Kruskal-Wallis Test χ2 (Df=1).
*, **, *** significant at the 10%, 5%, or 1% level respectively
Table IV-S. Hurricane Risk Perceptions (n=804) (Unweighted Data)
Texas
Florida
K-W test
(n=347)
(n=457)
TX=FL
Perceived to live in Evacuation Zone (Yes=1)
0.43
0.28
0.46
29.7***
Likely Conditions - High Winds and Objects Blowing a
4.29
4.29
4.29
0.7
Likely Conditions - Storm Surge a
3.11
3.30
2.97
10.1***
Likely Conditions - Inland Flooding a
3.78
3.93
3.66
9.3***
a
Likely Impacts - Mortality and Morbidity
3.20
3.28
3.14
2.5
a
Likely Impacts – Looting
2.82
2.89
2.77
2.1
Likelihood of Hurricane in Next Yearb
45.77
45.30
46.13
0.2
c
Hurricane Risks – Catastrophic
3.82
3.94
3.73
5.5**
Hurricane Risks – Controllability d
2.29
2.27
2.30
0.1
a
How likely would each of the following conditions be in the general area where you live if a major hurricane (Category 3 or higher) hit your
area? (Extremely Unlikely=1; Extremely Likely=5)
b
Please move the blue marker to the place on the line that describes your best estimate of how likely you think a major hurricane (Category 3
or higher, that is winds of 110 mph or higher) will occur in the general area where you live in the next year? (Respondents provided an open
ended response).
c
For each hazard listed, is it a risk that kills people one at a time (chronic risk) or a risk that kills large numbers of people at once (catastrophic
risk)? (Chronic (kills people one at a time)=1; Catastrophic (kills large numbers of people at once)=5)
d
How much personal control do people exposed to each hazard have over it? That is, to what extent can they prevent mishaps or illnesses to
themselves from occurring, or reduce their severity if they do occur? (No personal control=1; Total personal control=5)
K-W – Kruskal-Wallis Test χ2 (Df=1).
*, **, *** significant at the 10%, 5%, or 1% level respectively
Variable
Mean
Table V-S. Evacuation Motivations and Barriers (n=804) (Unweighted Data)
Item
Mean
Texas
(n=347)
Florida
(n=457)
z-scorea
TX=FL
3.98
3.33
4.07
3.53
3.91
3.17
1.67*
3.69***
Motivationsb
… because I want to keep my family safe
… so I would not be stuck in the area after the hurricane
Barriersc
… I do not know how to evacuate
1.71
1.65
1.75
0.33
… my pet(s) make it difficult to evacuate
2.09
1.97
2.19
1.80*
… I lack transportation
1.61
1.63
1.60
0.96
… my health or disabilities make it difficult to evacuate
1.71
1.73
1.69
0.95
… I have a family member whose health/disability makes it difficult to evacuate
1.73
1.79
1.68
1.74*
House Vulnerable / Safe
… because my house is vulnerable to hurricane storm surge b
2.63
2.75
2.54
2.22**
… my house is safe from hurricane storm surge c
3.16
3.00
3.28
2.87***
House Vulnerable–Surge alpha-factor (from above two items )d
0.00
0.09
-0.07
3.13***
… my house is safe from hurricane winds c
2.86
2.59
3.07
5.47***
… because my house is vulnerable to hurricane winds b
2.98
3.20
2.81
4.06***
House Vulnerable–Winds alpha-factor (from above two items )d
0.00
0.18
-0.13
5.91***
Trust
… because I trust hurricane warnings and forecasts b
3.57
3.58
3.56
0.27
… I distrust hurricane warnings and forecasts c
1.99
2.01
1.98
0.85
Trust Information alpha-factor (from above two items)e
0.00
0.00
0.00
0.21
a
Z-score from Mann-Whitney U test for two independent samples (absolute value of Z; asymptotic significance).
b“
For each of the following statements, please indicate how strongly you agree or disagree for your own personal situation. If a hurricane threatened, I
would evacuate…”
c“
For each of the following statements, please indicate how strongly you agree or disagree for your own personal situation. If a hurricane threatened, I
would shelter in place, and would NOT evacuate, because…”
d
Alpha-factoring essentially reverse scores the “safe” item so higher factor score indicates a higher level of perceived vulnerability with respect to wind
risks or surge risks.
e
The alpha-factoring essentially reverse scores the “don’t trust” item so a higher factor score indicates a higher level of trust in hurricane information.
For all individual items the response scale was: Strongly Disagree=1; Disagree=2; Neither Agree nor Disagree=3; Agree=4; Strongly Agree=5.
*, **, *** significant at the 10%, 5%, or 1% level respectively
Table VI-S. Prior Experience and Preparation (n=804) (Weighted and Unweighted Data)
Variable
Mean
Texas
(n=347)
Z-scored
TX=FL
Florida
(n=457)
Weighted Data
Totals weighted to be representative of all areas sampled and state-level data weighted to be representative of the areas sampled at
state level
Prior Experience – Evacuated a
45.5%
63.2%
29.2%
Prior Experience – Severity of Impacts b
2.74
2.68
2.79
Prior Preparatory Action – Developed An Evacuation Plan c
58.3%
66.2%
51.1%
Prior Response – Have Evacuateda
39.6%
55.9%
27.1%
Prior Experience Severity Scaleb
2.76
2.70
2.80
Developed An Evacuation Planc
57.5%
62.5%
53.6%
9.29*
**
2.53*
*
4.03*
**
Unweighted Data
a
8.3**
*
1.4
2.5**
In response to a hurricane threat or due to a hurricane, have you or has anyone in your household ever evacuated or left your residence to go
someplace safer?
b
Overall, how severe have the impacts of your own hurricane experience(s) been? (Not at all severe=1, Moderately severe=3, Extremely
severe=5). "No Experience" recoded as "1"
c
Which of the following have you done to prepare for a hurricane threat in the past? Developed an evacuation plan
d
Z-score from Mann-Whitney U test for two independent samples (absolute value of Z; asymptotic significance).
*, **, *** significant at the 10%, 5%, or 1% level respectively
Table VII-S. Use of Different Sources of Information (Weighted and Unweighted Data)
Sourcesa
Mean
(N=804)
Texas
(n=347)
Florida
(n=457)
z-scoreb
TX=FL
Factor 1
Public Sources
Factor 2
Personal Sources
Weighted Data
Totals weighted to be representative of all areas sampled and state-level data weighted to be representative of the areas sampled at state level
National Weather Service/Weather Forecasting Office
4.28
4.26
4.32
0.99
0.84
National Hurricane Center
4.32
4.20
4.43
3.66***
0.83
Public officials/ emergency managers
3.61
3.73
3.52
2.53**
0.68
Your family, friends, or colleagues
3.22
3.21
3.22
0.70
0.10
Your own experience
3.36
3.37
3.33
0.10
0.25
Religious leaders or clergy
1.54
1.75
1.40
5.61***
-0.06
Variance explained by each rotated factor
32.3%
0.03
0.04
0.19
0.77
0.65
0.64
24.5%
Unweighted Data
National Weather Service/Weather Forecasting Office
4.36
4.30
4.41
1.59
0.84
National Hurricane Center
4.36
4.14
4.53
5.87***
0.83
Public officials/ emergency managers
3.64
3.68
3.61
0.64
0.68
Your family, friends, or colleagues
3.24
3.24
3.24
0.17
-0.02
Your own experience
3.43
3.38
3.47
1.33
0.14
Religious leaders or clergy
1.54
1.63
1.48
2.48**
-0.03
-0.03
-0.03
0.10
0.77
0.65
0.64
Variance explained by each rotated factor
32.3%
24.5%
Q10. In the event of a hurricane threat, how often would you use the following to get information about the risk of an approaching hurricane?
(Never=1; About half the time=3; Always= 5)
b
Z-score from Mann-Whitney U test for 2 independent samples.
c
Principal components analysis with varimax rotation was performed on these items and two factors retained (Initial eigenvalues 2.17 and 1.2
respectively, explaining 56.8% variance cumulatively).
a
*, **, *** significant at the 10%, 5%, or 1% level respectively
Table VIII-S. Perceptions of Hurricane Forecast Information (n=804) (Weighted and Unweighted Data)
Sources
Mean
Std Dev
Min
Max
Texas
(n=347)
Florida
(n=457)
Z-scorec
TX=FL
Weighted Data
Totals weighted to be representative of all areas sampled and state-level data weighted to be representative of the areas sampled at state level
Information Usefulness a
Information Accuracy b
66.40
3.73
10.92
0.82
11
1
77
5
64.68
3.78
67.98
3.68
3.37***
1.87*
Unweighted Data
Information Usefulnessa
67.15
10.66
11.00
77.00
65.79
68.18
-3.02***
Information Accuracy b
3.80
0.83
1.00
5.00
3.81
3.80
-0.29
a
“How useful to you personally is the following information that may be provided with a hurricane forecast?” (Not at all Useful=1; Somewhat
Useful=4; Extremely Useful=7) (Location of landfall; Time of landfall; Maximum sustained wind speed; Duration of storm; Size of storm (e.g. radius,
diameter); Storm surge depths; Inland flooding from rainfall; Tornadoes caused by hurricanes ; Changes in hurricane strength; Information about
storm impacts; Information about how to prepare and respond). Information Usefulness is scored as the sum of these 11 items.
b
“In your opinion, how accurate are hurricane forecasts overall at this time?” (Not at all accurate=1; Somewhat accurate=3; Extremely accurate=5).
c
Z-score from Mann-Whitney U test for two independent samples (absolute value of Z; asymptotic significance).
*, **, *** significant at the 10%, 5%, or 1% level respectively