Table 3 Descriptive characteristics of behavioral determinants and knowledge items at baseline and follow-up and the change from baseline to follow-up

How high or low are the chances of you getting health problems from arsenic if it is in your well water?

Perceived vulnerability

0.50

0.61

0.31

0.75

0.67

0.32

0.25

0.06

0.177

How high or low are the chances of someone in your household getting health problems from arsenic if it is in your well water?

Perceived vulnerability

0.75

0.62

0.31

0.75

0.65

0.32

0.0

0.04

0.387

How high or low are the chances of you getting health problems from arsenic if you drink water from an arsenic filter?

Perceived vulnerability

0.25

0.20

0.23

0.25

0.25

0.30

0.0

0.05

0.137

I have been drinking this water for a long time with no health problems, so I am not concerned about arsenic in my well water.

Perceived vulnerability

0.25

0.37

0.36

0.0

0.28

0.36

−0.25

−0.08

0.016

Because no one in my house has developed health problems from arsenic, I am not concerned about arsenic in my well water.

Perceived vulnerability

0.25

0.32

0.35

0.0

0.29

0.35

−0.25

−0.03

0.212

I can afford to fix my arsenic filter if it breaks.

Perceived cost

0.75

0.61

0.36

0.75

0.66

0.39

0.0

0.05

0.088

Of all the things I have to worry about, the arsenic filter is not at the top of my list.

Competing Priorities

0.25

0.42

0.37

0.75

0.56

0.40

0.50

0.14

0.027

If given the choice, I would prefer bottled water over water from an arsenic filter.

User preferences

0.50

0.46

0.36

0.50

0.45

0.36

0.0

−0.01

0.495

The tribal water system in my area has a safe level of arsenic.

Perceived safety of tribal water system

0.50

0.36

0.29

0.50

0.49

0.31

0.0

0.12

0.003

How many people in your community have arsenic in their wells?

Perceived extent of contamination in community

0.75

0.60

0.26

0.50

0.62

0.30

−0.25

0.03

0.863

How many people in your community with arsenic in their wells drink this water without filtration?

Descriptive norm

0.75

0.71

0.26

0.75

0.61

0.28

0.0

−0.10

0.003

How many people in your community with arsenic in their wells cook with this water without filtration?

Descriptive norm

0.75

0.75

0.23

0.75

0.64

0.28

0.0

−0.11

0.001

How many people in your community with arsenic in their wells use bottled water for drinking?

Descriptive norm

0.25

0.29

0.21

0.25

0.39

0.28

0.0

0.10

0.004

How many people in your community with arsenic in their wells use an arsenic filter for their drinking water?

Descriptive norm

0.25

0.16

0.18

0.25

0.30

0.27

0.0

0.14

0.001

How many people in your community with arsenic in their wells use an arsenic filter for their cooking water?

Descriptive norm

0.25

0.17

0.22

0.25

0.29

0.27

0.0

0.11

0.002

How much would people who are important to you approve or disapprove of you using water containing high arsenic for drinking?

Injunctive norm

0.25

0.22

0.26

0.00

0.11

0.22

−0.25

−0.11

0.012

How much would people who are important to you approve or disapprove of you using water containing high arsenic for cooking?

Injunctive norm

0.25

0.23

0.26

0.00

0.11

0.22

−0.25

−0.12

0.008

How sure are you that you can get drinking water with a safe level of arsenic?

Self-efficacy

0.50

0.51

0.34

0.75

0.63

0.37

0.25

0.12

0.062

How sure are you that you can get water for cooking with a safe level of arsenic?

Self-efficacy

0.50

0.49

0.35

0.75

0.66

0.34

0.25

0.17

0.004

How sure are you that you could find local resources to learn about arsenic in water?

Self-efficacy

0.25

0.40

0.36

0.50

0.54

0.36

0.25

0.13

0.016

How sure are you that local resources would help you resolve an arsenic-related problem with your private well?

Self-efficacy

0.25

0.36

0.36

0.50

0.49

0.36

0.25

0.13

0.016

How sure are you that you can use your arsenic filter faucet every time you need water for drinking in your home?

Self-efficacy

1.00

0.86

0.22

1.00

0.82

0.27

0.00

−0.04

0.034

How sure are you that you can use your arsenic filter faucet every time you need water for cooking in your home?

Self-efficacy

1.00

0.86

0.22

1.00

0.84

0.26

0.00

−0.02

0.199

How sure are you that you will be able to buy a new arsenic filter cartridge when needed?

Self-efficacy

1.00

0.75

0.31

0.75

0.68

0.32

−0.25

−0.07

0.169

How sure are you that you yourself can change your arsenic filter cartridge when needed?

Self-efficacy

1.00

0.69

0.37

0.75

0.63

0.40

−0.25

−0.06

0.050

How sure are you that you will be able to use your arsenic filter consistently over the next year?

Self-efficacy

1.00

0.92

0.18

1.00

0.88

0.24

0.00

−0.04

0.051

How sure are you that you will be able to use your filter consistently over the next five years?

Self-efficacy

1.00

0.85

0.22

1.00

0.80

0.30

0.00

−0.05

0.007

How committed do you feel to drinking water only from your arsenic filter faucet?

Commitment strength

1.00

0.79

0.26

1.00

0.79

0.28

0.00

−0.01

0.808

How committed do you feel to cooking with water only from your arsenic filter faucet?

Commitment strength

1.00

0.82

0.25

1.00

0.81

0.28

0.00

0.00

0.655

Overall arsenic knowledge

Knowledge

0.71

0.66

0.28

0.71

0.65

0.29

0.00

−0.01

0.940

Name two health conditions that can happen from arsenic exposure.

Knowledge

0.50

0.54

0.44

0.50

0.54

0.41

0.00

0.00

0.819

Name two tasks where it is OK to use water with high arsenic.

Knowledge

1.00

0.61

0.44

1.00

0.61

0.45

0.00

−0.01

0.781

Name two tasks where it is NOT OK to use water with high arsenic.

Knowledge

1.00

0.76

0.35

1.00

0.72

0.40

0.00

−0.04

0.442

How could you remove arsenic from drinking water?

Knowledge

1.00

0.81

0.39

1.00

0.82

0.39

0.00

0.00

0.312