Online Supplement: “Search and Choice in Online Consumer Auctions” Appendix A: Keywords used to determine if an auction is a competing auction in a given category Product

Keywords used to determine substitutes

Products filtered out from the search results

Fisher Price gym

Fisher-Price Aquarium gym

None

Harry Potter audio book 6

Harry Potter and The Half-Blood Prince book

Titles other than that specified, Harry Potter non-audio books, instances of this audio book as part of a set or a lot, collector editions, items sold outside the U.S.

Harry Potter boxed set

Harry Potter boxed set, Harry Potter box set

Collectors’ editions, smaller sets (with fewer than all books), lots, bundles of this set with other items

Pampers Swaddlers newborn diapers

Pampers Swaddlers newborn diapers

Not containing either newborn or NB in the description

Dr. Brown baby bottles

Dr./Dr Brown baby bottles

None

Happy Hippo gym

Happy Hippo gym

None

Harry Potter book 6

Harry Potter and The Half-Blood Prince book

Titles other than that specified, Harry Potter audio books, instances of this audio book as part of a set or a lot, collector editions, items sold outside the U.S.

Fisher Price baby rocker

Fisher Price rocker

Nothing

The Secret audio book

The Secret Rhonda Byrne

Titles other than that specified, non-audio books, instances of this audio book as part of a set or a lot, collector editions, items sold outside the U.S.

1

Appendix B: Plots of Relative Prices for Different Product Categories over Time

2

Appendix C: Model in Table 3 without random coefficients: Results of Logit Regressions with state dependence, under independence of observations1 State Dependence Search Incentive × Price Duration in days Price Shipping Open Reserve Secret Reserve State Dependence State Dependence × Search incentive State Dependence × Time Left Loyalty Loyalty × Search incentive Loyalty × Time Left Bid Rate Number of bids Increment rate Log likelihood function AIC BIC Adjusted BIC McFadden Pseudo R2 Adjusted R2 Num. individuals/observations Number of coefficients incl. intercept

Number of significant coeff

Loyalty

Encompassing

Coefficient

Std. Error

Coefficient

Std. Error

Coefficient

Std. Error

-0.143*** -0.371*** -0.172*** -0.059 -0.152*** 0.701*** 2.004***

0.068 0.051 0.050 0.057 0.047 0.084 0.106

-0.162*** -0.075 -0.209*** 0.129** -0.061 0.222**

0.064 0.058 0.057 0.062 0.050 0.092

-0.159*** -0.141** -0.218*** 0.096 -0.077 0.356*** 0.630***

0.064 0.060 0.057 0.062 0.050 0.096 0.129

-0.344** -0.033***

0.153 0.007

-0.126 -0.012

0.188 0.009

1.646*** -0.107 -0.025*** -0.141** 0.007 0.202*

0.096 0.140 0.007 0.064 0.011 0.118

0.004 -0.097 0.149

0.009 0.068 0.131

1.917*** -0.161 -0.031*** -0.144** 0.021** 0.221*

0.080 0.118 0.006 0.063 0.010 0.118

-2072.52 1.130 1.179 1.139 0.192

-1774.85 0.970 1.019 0.979 0.308

-1756.83 0.962 1.016 0.969 0.315

0.186

0.303

0.309

1190/3718

1190/3718

1190/3718

29

29

32

11

11

11

* p-value