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Table 3 Maximum likelihood estimation of sample selection and ordered responses

From: Consumer response to media information: the case of grapefruit-medicine interaction

 

Outcome equation (Y21))

Selection equation (Y12))

 

Estimated parameters

Standard error

Estimated parameters

Standard error

Thresholds 1

0.059

(1.348)

−2.550b

(0.242)

Thresholds 2

3.229b

(1.059)

-

 

Age

0.020a

(0.011)

0.013b

(0.004)

Gender

0.103

(0.125)

−0.029

(0.056)

Income

−0.046

(0.059)

0.012

(0.026)

Education

0.174

(0.124)

0.117b

(0.056)

Yes warning

1.505b

(0.566)

0.798b

(0.314)

No warning

0.273

(0.396)

0.208

(0.186)

Occasionally consumed

1.646b

(0.539)

0.780b

(0.214)

Frequently consumed

2.150b

(0.669)

1.754b

(0.24)

Trust

-

 

0.012

(0.066)

Influence

-

 

0.173b

(0.067)

Search

-

 

0.257b

(0.063)

Positive tone

0.845b

(0.177)

-

 

Negative tone

−0.277a

(0.167)

-

 

Positive frequency

0.050

(0.038)

-

 

Negative frequency

−0.038

(0.038)

-

 

Old news

−0.398b

(0.165)

-

 

New news

−0.505b

(0.181)

-

 

Age*Yes warning

−0.037b

(0.011)

−0.006

(0.006)

Age*No warning

−0.007

(0.009)

−0.003

(0.004)

Age*Occasionally consumed

−0.035b

(0.010)

−0.011b

(0.004)

Age*Frequently consumed

−0.030b

(0.011)

−0.022b

(0.005)

ρ

0.278

(0.457)

  

LR test (H o  : ρ = 0), χ 2 (1)

 

270.99b

Observations

 

3497

Log Likelihood

 

−1700.55

Wald test, χ 2 (18)

 

169.51

  Estimated probabilities

Mean

Min

Max

p(y1 = 1)

0.157

0.016

0.654

p(y1 = 1, y2 = 0)

0.011

0.000

0.247

p(y1 = 1, y2 = 1)

0.127

0.134

0.455

p(y1 = 1, y2 = 2)

0.019

0.000

0.496

  1. b and a indicates that estimated parameters are significantly different from zero at 5 % and 10 % levels, respectively
  2. 1) Y2 = 0 if respondents consumed less than before, Y2 = 1 if respondents did not change their consumption and Y2 = 2 if respondents consume more than before
  3. 2) Y1 = 1 if respondents have been exposed to grapefruit/grapefruit juice news over the past month