title: How important is selection? Experimental vs. non-experimental measures of the income gains from migration

authors: McKenzie, David

subjects: New Zealand

abstract: How much do migrants stand to gain in income from moving across borders? Answering this question is complicated by non-random selection of migrants from the general population, which makes it hard to obtain an appropriate comparison group of non-migrants. New Zealand allows a quota of Tongans to immigrate each year with a random ballot used to choose among the excess number of applicants. A unique survey conducted by the authors allows experimental estimates of the income gains from migration to be obtained by comparing the incomes of migrants to those who applied to migrate, but whose names were not drawn in the ballot, after allowing for the effect of non-compliance among some of those whose names were drawn. We also conducted a survey of individuals who did not apply for the ballot. Comparing this non-applicant group to the migrants enables assessment of the degree to which non-experimental methods can provide an unbiased estimate of the income gains from migration. We find evidence of migrants being positively selected in terms of both observed and unobserved skills. As a result, non-experimental methods other than instrumental variables are found to overstate the gains from migration by 20–82%, with difference-in-differences and bias-adjusted matching estimators performing best among the alternatives to instrumental variables. (JEL: J61, F22, C21)

text: How important is selection? Experimental vs. non-experimental measures of the income gains from migration How much do migrants stand to gain in income from moving across borders? Answering this question is complicated by non-random selection of migrants from the general population, which makes it hard to obtain an appropriate comparison group of non-migrants. New Zealand allows a quota of Tongans to immigrate each year with a random ballot used to choose among the excess number of applicants. A unique survey conducted by the authors allows experimental estimates of the income gains from migration to be obtained by comparing the incomes of migrants to those who applied to migrate, but whose names were not drawn in the ballot, after allowing for the effect of non-compliance among some of those whose names were drawn. We also conducted a survey of individuals who did not apply for the ballot. Comparing this non-applicant group to the migrants enables assessment of the degree to which non-experimental methods can provide an unbiased estimate of the income gains from migration. We find evidence of migrants being positively selected in terms of both observed and unobserved skills. As a result, non-experimental methods other than instrumental variables are found to overstate the gains from migration by 20–82%, with difference-in-differences and bias-adjusted matching estimators performing best among the alternatives to instrumental variables. (JEL: J61, F22, C21)

year: 2010

title: The effects of relatedness, social contact, and sex on observational learning in rats (Rattus norvegicus)

authors: Tulloch, Bridget

subjects: Rats

abstract: Kin recognition is the ability to identify a conspecific as a relative and can occur even when animals are complete strangers.  By being able to recognise relatives, animals are able to give preferential treatment to those with which they share genes.  Recognition may occur by either direct familiarisation (learning a phenotypic cue that reliably correlates to kinship), or by indirect familiarisation (learning kinship relationships through previous encounters).  Rats (Rattus norvegicus) can recognise kin, however to what degree kin recognition is mediated by genetics (direct familiarisation) or social relationships (indirect familiarisation) are unknown; the influences of kinship and familiarity on the ability to learn from a conspecific is also unknown.  Furthermore, the sex of an animal can also influence its ability to learn but this effect has received little attention in the literature, particularly when considering observational learning tasks.  I assessed if relatedness and/or familiarity influenced a rat's ability to learn through observation, and if gender relationships influence the learning process.  Eighty rats ( observers ) were given the opportunity to observe a  demonstrator  rat press a joystick in a given direction to obtain a food reward.  Observers watched a demonstrator that had one of the following relationships with them: related and familiar, related and unfamiliar, unrelated and familiar, or unrelated and unfamiliar.  When observers were given the opportunity to manipulate the joystick, the number of sniffs of the joystick, the latency to first move the joystick and the total number of presses were recorded.  Rats that were both familiar and related to the demonstrator consistently performed better than any other treatment group; furthermore, rats that were familiar with the demonstrator performed the task more efficiently than rats that were not familiar with the demonstrator.  When the demonstrators and observers were related, the observers produced more presses and sniffs of the joystick while having a lower latency to the first push   In addition, male observers learnt better than females regardless of the demonstrator sex, with males that were familiar to their demonstrator making nearly twice as many pushes than any other treatment group. The results from this study are discussed in relation to both the mechanisms of direct and indirect recognition and the potential adaptive value on kin discrimination in the learning process.  The home range hypothesis may explain why gender differences in learning were found: male rats have larger home ranges than females.  Male rat will regularly encounter more rats than females and would need to ascertain if unfamiliar individuals are relatives.  Females remain closer to natal sites and as such are more likely to encounter kin and therefore may not need as well as developed kin recognition ability.

text: The effects of relatedness, social contact, and sex on observational learning in rats (Rattus norvegicus) Kin recognition is the ability to identify a conspecific as a relative and can occur even when animals are complete strangers.  By being able to recognise relatives, animals are able to give preferential treatment to those with which they share genes.  Recognition may occur by either direct familiarisation (learning a phenotypic cue that reliably correlates to kinship), or by indirect familiarisation (learning kinship relationships through previous encounters).  Rats (Rattus norvegicus) can recognise kin, however to what degree kin recognition is mediated by genetics (direct familiarisation) or social relationships (indirect familiarisation) are unknown; the influences of kinship and familiarity on the ability to learn from a conspecific is also unknown.  Furthermore, the sex of an animal can also influence its ability to learn but this effect has received little attention in the literature, particularly when considering observational learning tasks.  I assessed if relatedness and/or familiarity influenced a rat's ability to learn through observation, and if gender relationships influence the learning process.  Eighty rats ( observers ) were given the opportunity to observe a  demonstrator  rat press a joystick in a given direction to obtain a food reward.  Observers watched a demonstrator that had one of the following relationships with them: related and familiar, related and unfamiliar, unrelated and familiar, or unrelated and unfamiliar.  When observers were given the opportunity to manipulate the joystick, the number of sniffs of the joystick, the latency to first move the joystick and the total number of presses were recorded.  Rats that were both familiar and related to the demonstrator consistently performed better than any other treatment group; furthermore, rats that were familiar with the demonstrator performed the task more efficiently than rats that were not familiar with the demonstrator.  When the demonstrators and observers were related, the observers produced more presses and sniffs of the joystick while having a lower latency to the first push   In addition, male observers learnt better than females regardless of the demonstrator sex, with males that were familiar to their demonstrator making nearly twice as many pushes than any other treatment group. The results from this study are discussed in relation to both the mechanisms of direct and indirect recognition and the potential adaptive value on kin discrimination in the learning process.  The home range hypothesis may explain why gender differences in learning were found: male rats have larger home ranges than females.  Male rat will regularly encounter more rats than females and would need to ascertain if unfamiliar individuals are relatives.  Females remain closer to natal sites and as such are more likely to encounter kin and therefore may not need as well as developed kin recognition ability.

year: 2007

title: Understanding the use of Māori and English in dual language picturebooks through a sociolinguistic lens

authors: Daly, Nicola

abstract: In this presentation I will explore the use of te reo Māori in English text in dual language picturebooks published in Aotearoa/New Zealand. A series of studies examining the frequency of Māori loanwords in children’s picturebooks (Daly 2007; Daly 2008; Macdonald & Daly, 2013) are presented showing that when books came out of a publishing company with a commitment to publishing Māori and Pasifika stories, the frequency of loanwords was much higher than in other contexts; but even when a survey of all picturebooks published in New Zealand between 1995 and 2005 was conducted, the frequency of loanwords was much higher than in previous studies of comparable literature, such as the New Zealand school journal (Macalister, 1999). Very few dual language picturebooks featuring Māori and English are produced in New Zealand (Daly 2016a; Daly 2016b). The synchronous or sequential format of having separate books for each language seems to be favoured. But it is in the parallel dual language format (where both languages are present in a single book) that the relative status of the two languages is evident. In the second part of the presentation the layout and comparative presentation of the two languages are explored in terms of size of font and order of languages, using a Linguistic Landscape framework (Landry & Bourhis, 1997). These uses of two languages within New Zealand children’s literature (both interlingual and dual language) are examined and considered in terms of Bell’s (1984) theory of Audience Design, considering whether writers and publishers of such literature are now catering for a wider and more bilingual audience and whether publishing such linguistically diverse material such linguistically diverse picturebooks may be contributing to the creation of a more bilingual society.

text: Understanding the use of Māori and English in dual language picturebooks through a sociolinguistic lens In this presentation I will explore the use of te reo Māori in English text in dual language picturebooks published in Aotearoa/New Zealand. A series of studies examining the frequency of Māori loanwords in children’s picturebooks (Daly 2007; Daly 2008; Macdonald & Daly, 2013) are presented showing that when books came out of a publishing company with a commitment to publishing Māori and Pasifika stories, the frequency of loanwords was much higher than in other contexts; but even when a survey of all picturebooks published in New Zealand between 1995 and 2005 was conducted, the frequency of loanwords was much higher than in previous studies of comparable literature, such as the New Zealand school journal (Macalister, 1999). Very few dual language picturebooks featuring Māori and English are produced in New Zealand (Daly 2016a; Daly 2016b). The synchronous or sequential format of having separate books for each language seems to be favoured. But it is in the parallel dual language format (where both languages are present in a single book) that the relative status of the two languages is evident. In the second part of the presentation the layout and comparative presentation of the two languages are explored in terms of size of font and order of languages, using a Linguistic Landscape framework (Landry & Bourhis, 1997). These uses of two languages within New Zealand children’s literature (both interlingual and dual language) are examined and considered in terms of Bell’s (1984) theory of Audience Design, considering whether writers and publishers of such literature are now catering for a wider and more bilingual audience and whether publishing such linguistically diverse material such linguistically diverse picturebooks may be contributing to the creation of a more bilingual society.

year: 2018