Master Seminar in Empirical Labor Economics (summer term 2024)
⇒ For a PDF-file including further information and a description of topics click here.
Topics:
1. The impact of regional mobility of working individuals on life and job satisfaction
2. After work shopping? Employment effects of a deregulation of shop opening hours in the German retail sector
3. Working hours mismatch and job mobility
4. Determinants of East-West migration in Germany
5. Overeducation and career mobility
Timetable:
Date | Location | |
Monday, 22.04.2024 12:00-14:00 h |
RW 6 (new ReWi) |
Kick-Off (introduction, organizational issues, assignment of topics) |
Sunday, 23.06.2024 23:59 h |
Deadline for submission of presentation slides and of a preliminary draft of the seminar paper to sekretariat.schank@uni-mainz.de | |
Wednesday, 26.06.2024 09:00-18:00 h |
03-150 Dekanatssaal (new ReWi) |
Presentations of seminar papers |
Sunday, 07.07.2024 23:59 h |
Deadline for submission of the final seminar thesis to sekretariat.schank@uni-mainz.de |
Further information:
We will send before the first meeting an http-address where participants can state their preferences by ranking the topics from 1 (most preferred) to 5 (least preferred), but students can modify their preferences at the end of the introductory meeting. Topics will be assigned (according to the stated preferences) to groups of two or three students directly after the introductory meeting. Students within groups can work together and use a joint do-file in Stata. Group members should also present their results jointly. However, note that each person should write up her/his seminar thesis independently. The thesis should cover not more than 12 pages, including tables and figures, but without references.
The main task is to investigate the research topic using Stata and to write up the findings in the style of a research paper. Therefore, it is expected that students are able to work independently with Stata. Students are expected to use the reference articles as a benchmark for their own investigations, though not all regressions of the papers have to be mimicked. Neither is it the goal to reproduce exactly the same results as the papers which are already based on the SOEP. Students should adhere to the requirements stated above and should discuss the outline of their paper with their supervisor.
We will supply a student version of the German Socio-Economic Panel (SOEP), the data-set to be used for the analysis. Instructions on how to access the data will be provided in the first meeting.
Students need to submit an electronic version of their seminar thesis by e-mail to sekretariat.schank@uni-mainz.de, together with the literature cited in the thesis (except for the papers referenced above), a Stata log-file and a do-file which produces all results reported in the seminar thesis. Before submission, students should make sure that the do-file runs through from the beginning to the end and should also appropriately comment in the do-file which table, etc., is produced by which command.
Further formal requirements will be discussed during the introductory meeting. The slides from this introductory meeting will be downloadable from ILIAS. Participants are expected to follow all guidelines listed on the slides.
Contact
Prof. Dr. Thorsten Schank (schank@uni-mainz.de)
Alexander Moog, M.Sc. (amoog@uni-mainz.de)
Master Seminar in Empirical Labor Economics (summer term 2023)
⇒ For a PDF-file including further information and a description of topics click here.
Topics:
1. Working from home, hours worked, wages and job satisfaction
2. Sickness-related absence and career mobility
3. The effect of locus of control on job search and the job-finding rate
4. The gender reservation wage gap
5. Differences in education, earnings and employment between immigrants and natives
6. Mozart or Pelé? The effects of adolescents' participation in music and sports
Timetable:
Date | Location | |
Thursday, 27.04.2023 10:00-12:00 h |
HS VI (old ReWi) |
Kick-Off (introduction, organizational issues, assignment of topics) |
Sunday, 25.06.2023 23:59 h |
Deadline for submission of presentation slides and of a preliminary draft of the seminar paper to sekretariat.schank@uni-mainz.de | |
Thursday, 29.06.2023 09:00-18:00 h |
HS VI (old ReWi) |
Presentations of seminar papers |
Wednesday, 12.07.2023 23:59 h |
Deadline for submission of the final seminar thesis to sekretariat.schank@uni-mainz.de |
Further information:
We will send before the first meeting an http-address where participants can state their preferences by ranking the topics from 1 (most preferred) to 5 (least preferred), but students can modify their preferences at the end of the introductory meeting. Topics will be assigned (according to the stated preferences) to groups of two or three students directly after the introductory meeting. Students within groups can work together and use a joint do-file in Stata. Group members should also present their results jointly. However, note that each person should write up her/his seminar thesis independently. The thesis should cover not more than 12 pages including tables and figures, but without references.
The main task is to investigate the research topic, using Stata, and to write up the findings in the style of a research paper. Students are expected to use the reference articles as a benchmark for their own investigations, though not all regressions of the papers have to be mimicked. Neither is it the goal to reproduce exactly the same results as the papers which are already based on the SOEP. Students should adhere to the requirements stated above and should discuss the outline of their paper with their supervisor.
We will supply a student version of the German Socio Economic Panel (SOEP), the data-set to be used for the analysis. Instructions on how to access the data will be provided in the first meeting.
Students need to submit an electronic version of their seminar thesis by e-mail to sekretariat.schank@uni-mainz.de, together with the literature cited in the thesis (except for the papers referenced above), a Stata log-file and a do-file which produces all results reported in the seminar thesis. Before submission, students should make sure that the do-file runs through from the beginning to the end and should also appropriately comment in the do-file which table etc. is produced by which command.
Further formal requirements will be discussed during the introductory meeting. The slides from this introductory meeting will be downloadable from ILIAS. Participants are expected to follow all guidelines listed on the slides.
Contact
Prof. Dr. Thorsten Schank (schank@uni-mainz.de)
Ying Liang, M.Sc. (liang.ying@uni-mainz.de)
Master Seminar in Empirical Labor Economics (summer term 2022)
⇒ For a PDF-file including further information and a description of topics click here.
Topics:
1. The impact of performance-related pay on job satisfaction
2. Sickness-related absence and career mobility
3. The effect of locus of control on job search and the job-finding rate
4. The effect of perceived unfairness on the individual well-being and career
5. Why do low-educated workers invest less in further training?
6. Mozart or Pelé? The effects of adolescents' participation in music and sports
Timetable:
Date | Location | |
Thursday, 28.04.2022 10:00-12:00 h |
HS VII (old ReWi) |
Kick-Off (introduction, organizational issues, assignment of topics) |
Sunday, 19.06.2022 23:59 h |
Deadline for submission of presentation slides and of a preliminary draft of the seminar paper to sekretariat.schank@uni-mainz.de | |
Thursday, 23.06.2022 09:00-18:00 h |
03-150 Dekanatssaal (new ReWi) |
Presentations of seminar papers |
Wednesday, 06.07.2022 23:59 h |
Deadline for submission of the final seminar thesis to sekretariat.schank@uni-mainz.de |
Further information:
We will send before the first meeting an http-address where participants can state their preferences by ranking the topics from 1 (most preferred) to 5 (least preferred), but students can modify their preferences at the end of the introductory meeting. Topics will be assigned (according to the stated preferences) to groups of two or three students directly after the introductory meeting. Students within groups can work together and use a joint do-file in Stata. Group members should also present their results jointly. However, note that each person should write up her/his seminar thesis independently. The thesis should cover not more than 12 pages including tables and figures, but without references.
The main task is to investigate the research topic, using Stata, and to write up the findings in the style of a research paper. Students are expected to use the reference articles as a benchmark for their own investigations, though not all regressions of the papers have to be mimicked. Neither is it the goal to reproduce exactly the same results as the papers which are already based on the SOEP. Students should adhere to the requirements stated above and should discuss the outline of their paper with their supervisor.
We will supply a student version of the German Socio Economic Panel (SOEP), the data-set to be used for the analysis. Instructions on how to access the data will be provided in the first meeting.
Students need to submit an electronic version of their seminar thesis by e-mail to sekretariat.schank@uni-mainz.de, together with the literature cited in the thesis (except for the papers referenced above), a Stata log-file and a do-file which produces all results reported in the seminar thesis. Before submission, students should make sure that the do-file runs through from the beginning to the end and should also appropriately comment in the do-file which table etc. is produced by which command.
Further formal requirements will be discussed during the introductory meeting. The slides from this introductory meeting will be downloadable from ILIAS. Participants are expected to follow all guidelines listed on the slides.
Contact
Prof. Dr. Thorsten Schank (schank@uni-mainz.de)
Ying Liang, M.Sc. (liang.ying@uni-mainz.de)
Master Seminar in Empirical Labor Economics (summer term 2021)
⇒ For a PDF-file including further information and a description of topics click here.
Topics:
1. Does it pay off for men to marry?
2. The impact of regional mobility of working individuals on life and job satisfaction
3. Differences in education, earnings and employment between immigrants and natives
4. The internet effects on the individual job finding rate
5. The effect of perceived unfairness on the individual well-being and career
Timetable:
Date | Location | |
Thursday, 15.04.2021 10:00-12:00 h |
online via MS Teams |
Kick-Off (introduction, organizational issues, assignment of topics) |
Sunday, 06.06.2021 23:59 h |
Deadline for submission of presentation slides and of a preliminary draft of the seminar paper to sekretariat.schank@uni-mainz.de | |
Thursday, 10.06.2021 09:00-18:00 h |
online via MS Teams |
Presentations of seminar papers |
Wednesday, 23.06.2021 23:59 h |
Deadline for submission of the final seminar thesis to sekretariat.schank@uni-mainz.de |
Further information:
We will send before the first meeting an http-address where participants can state their preferences by ranking the topics from 1 (most preferred) to 5 (least preferred), but students can modify their preferences at the end of the introductory meeting. Topics will be assigned (according to the stated preferences) to groups of two or three students directly after the introductory meeting. Students within groups can work together and use a joint do-file in Stata. Group members should also present their results jointly. However, note that each person should write up her/his seminar thesis independently. The thesis should cover not more than 12 pages including tables and figures, but without references.
The main task is to investigate the research topic, using Stata, and to write up the findings in the style of a research paper. Students are expected to use the reference articles as a benchmark for their own investigations, though not all regressions of the papers have to be mimicked. Neither is it the goal to reproduce exactly the same results as the papers which are already based on the SOEP. Students should adhere to the requirements stated above and should discuss the outline of their paper with their supervisor.
We will supply a student version of the German Socio Economic Panel (SOEP), the data-set to be used for the analysis. Instructions on how to access the data will be provided in the first meeting.
Students need to submit an electronic version of their seminar thesis by e-mail to sekretariat.schank@uni-mainz.de, together with the literature cited in the thesis (except for the papers referenced above), a Stata log-file and a do-file which produces all results reported in the seminar thesis. Before submission, students should make sure that the do-file runs through from the beginning to the end and should also appropriately comment in the do-file which table etc. is produced by which command.
Further formal requirements will be discussed during the introductory meeting. The slides from this introductory meeting will be downloadable from ILIAS. Participants are expected to follow all guidelines listed on the slides.
Contact
Prof. Dr. Thorsten Schank (schank@uni-mainz.de)
Manuel Denzer M.Sc. (madenzer@uni-mainz.de)
Master Seminar in Empirical Labor Economics (summer term 2020)
Further information including a description of the topics can be downloaded here.
Topics:
1. A natural experiment on sick pay cuts, sickness absence and labor costs
2. After work shopping? Employment effects of a deregulation of shop opening hours in the German retail sector
3. Differences in the choice of job search channel and in the probability of finding a job between immigrants and natives
4. The internet effects on the individual job finding rate
5. The well-being consequences of spousal unemployment
Timetable:
Date | Location | |
Wednesday, 22.04.2020 14:00-16:00 h |
HS VII (Old ReWi building) |
Kick-Off (introduction, organizational issues, assigning topics) |
Sunday, 14.06.2020 23:59 h |
Deadline for submission of presentation slides and of a preliminary draft of the seminar paper to sekretariat.schank@uni-mainz.de | |
Thursday, 18.06.2020 08:00-16:00 h |
Senatssaal 07 232(NatFak) |
Presentations of seminar papers |
Sunday, 28.06.2020 23:59 h |
Deadline of submission of the final seminar thesis to sekretariat.schank@uni-mainz.de (the printout can be submitted the next day at Pedelloge in the ReWi-1 building) |
Further information:
We will send before the first meeting an http-address where participants can state their preferences by ranking the topics from 1 (most preferred) to 5 (least preferred), but students can modify their preferences at the end of the introductory meeting. Topics will be assigned (according to the stated preferences) to groups of two or three students directly after the introductory meeting. Students within groups can work together and use a joint do-file in Stata. Group members should also present their results jointly. However, note that each person should write up her/his seminar thesis independently. The thesis should cover not more than 12 pages including tables and figures, but without references.
The main task is to investigate the research topic, using Stata, and to write up the findings in the style of a research paper. Students are expected to use the reference articles as a benchmark for their own investigations, though not all regressions of the papers have to be mimicked. Neither is it the goal to reproduce exactly the same results as the papers which are already based on the SOEP. Students should adhere to the requirements stated above and should discuss the outline of their paper with their supervisor.
We will supply a student version of the German Socio Economic Panel (SOEP), the data-set to be used for the analysis. Instructions on how to access the data will be provided in the first meeting.
Students need to submit an electronic version of their seminar thesis by e-mail to sekretariat.schank@uni-mainz.de, together with the literature cited in the thesis (except for the papers referenced above), a Stata log-file and a do-file which produces all results reported in the seminar thesis. Before submission, students should make sure that the do-file runs through from the beginning to the end and should also appropriately comment in the do-file which table etc. is produced by which command.
Further formal requirements will be discussed during the introductory meeting. The slides from this introductory meeting will be downloadable from ILIAS. Participants are expected to follow all guidelines listed on the slides.
Contact
Prof. Dr. Thorsten Schank (schank@uni-mainz.de)
Manuel Denzer M.Sc. (madenzer@uni-mainz.de)
Master Seminar in Empirical Labor Economics (summer term 2019)
Further information including a description of the topics can be downloaded here.
Topics:
1. Do women have different roles than men on supervisory boards?
2. Does a gender remuneration gap exist among supervisory board directors?
3. Does a gender wage gap in executive boards exist and does it depend on the gender composition of the supervisory board?
4. Do women in supervisory boards increase the probability of having female executive directors?
5. Do women on boards affect firm performance when controlling for tacit knowledge?
Timetable:
Date |
Location |
|
Wednesday, 17.04.2019 14:00-16:00 |
HS VII (Old ReWi building) |
Kick-Off (introduction, organizational issues, assigning topics) |
Tuesday, 23.04.2019 12:00-14:00 |
HS VII (Old ReWi building) |
FAQ about the dataset and best practice in working with STATA |
Monday, 10.06.2019 23:59 |
| - |
Deadline for submission of presentation slides and of a preliminary draft of the seminar paper to sekretariat.schank@uni-mainz.de |
Thursday, 13.06.2019 09:00-13:00 |
HS VII (Old ReWi building) |
Presentations of seminar papers |
Sunday, 23.06.2019 23:59 |
| - |
Deadline of submission of the final seminar thesis to sekretariat.schank@uni-mainz.de (the printout can be submitted the next day at Pedelloge in the ReWi-1 building) |
Further information:
We will send before the first meeting an http-address where participants can state their preferences by ranking the topics from 1 (most preferred) to 6 (least preferred), but students can modify their preferences at the end of the introductory meeting. Topics will be assigned (according to the stated preferences) to groups of two or three students directly after the introductory meeting. Students within groups can work together and use a joint do-file in Stata. Group members should also present their results jointly. However, note that each person should write up her/his seminar thesis independently. The thesis should cover not more than 14 (+/- 1) pages including tables and figures, but without references.
The main task is to investigate the research topic, using Stata and based on the references above, and to write up the findings in the style of a research paper.
Students need to submit an electronic version of their seminar thesis per e-mail to sekretariat.schank@uni-mainz.de, together with the literature cited in the thesis (except for the papers referenced above), a Stata log-file and a do-file which produces all results reported in the seminar thesis. Students should make sure that the do-file runs through before submission and should also appropriately comment in the do-file which table etc. is produced by which command. Further formal requirements will be discussed during the introductory meeting. The slides from this introductory meeting will be downloadable from ILIAS. Participants are expected to follow all guidelines listed on the slides.
Contact:
Prof. Dr. Thorsten Schank (schank@uni-mainz.de)
M.A. Viktor Bozhinov (bozhinvi@uni-mainz.de)
Master Seminar in Empirical Labor Economics (summer term 2018)
Further information including a description of the topics can be downloaded here.
Topics:
1. Does it pay off for men to marry?
2. The relationship between body weight and wages
3. The effect of locus of control on job search and the job finding rate
4. The gender reservation wage gap
5. The impact of regional mobility of working individuals on life and job satisfaction
6. Mozart or Pelé. The effects of adolescents’ participation in music and sports
Timetable:
Date |
Location |
|
Thursday, 19.04.2018 12:00-14:00 |
HS VII (Rewi Altbau) |
Kick-Off (introduction, organizational issues, assigning topics) |
Thursday, 03.05.2018 10:00-17:30Friday, 04.05.2018 09:30-17:30 |
PC-Pool 00-275 |
Workshop: Introduction to the German Socio-economic Panel Study (participaton compulsory) See http://www.statistics.economics.uni-mainz.de/483.php for further information |
Monday, 11.06.2018 23:59 |
- | Deadline for submission of presentation slides and of a preliminary draft of the seminar paper to sekretariat.schank@uni-mainz.de |
Thursday, 14.06.2018 08:00–18:00 |
HS VII (Rewi Altbau) |
Presentations of seminar papers |
Sunday, 24.06.2018 23:59 |
- | Deadline of submission of the final seminar thesis to sekretariat.schank@uni-mainz.de (the printout can be submitted the next day at Pedelloge in the ReWi-1 building) |
Further information:
We will send before the first meeting an http-address where participants can state their preferences by ranking the topics from 1 (most preferred) to 6 (least preferred), but students can modify their preferences at the end of the introductory meeting. Topics will be assigned (according to the stated preferences) to groups of two or three students directly after the introductory meeting. Students within groups can work together and use a joint do-file in Stata. Group members should also present their results jointly. However, note that each person should write up her/his seminar thesis independently. The thesis should cover not more than 12 pages including tables and figures, but without references.
We will supply a student version of the German Socio Economic Panel (GSOEP), the data-set to be used for the analysis. Instructions on how to access the data will be provided in the first meeting. Note that we organize a two-day workshop on May 3rd and 4th, which is held by two staff members of the SOEP. They introduce the data-set and are happy to discuss any questions regarding the dataset and the documentation material. It is compulsory for seminar participants to attend this workshop.
The main task is to investigate the research topic, using Stata and based on the references above, and to write up the findings in the style of a research paper. Students should discuss (at a minimum) the outline of their paper with their supervisor.
Students need to submit an electronic version of their seminar thesis per e-mail to sekretariat.schank@uni-mainz.de, together with the literature cited in the thesis (except for the papers referenced above), a Stata log-file and a do-file which produces all results reported in the seminar thesis. Students should make sure that the do-file runs through before submission and should also appropriately comment in the do-file which table etc. is produced by which command.
Further formal requirements will be discussed during the introductory meeting. The slides from this introductory meeting will be downloadable from ILIAS. Participants are expected to follow all guidelines listed on the slides.
Contact:
Prof. Dr. Thorsten Schank (schank@uni-mainz.de)
Dr. Alexander Mosthaf (mosthaf@uni-mainz.de)
Master Seminar in Empirical Labor Economics (summer term 2017)
Further information including a description of the topics can be downloaded here.
Topics:
1. Wage discrimination between natives, first generation migrants and second generation migrants.
2. The relationship between locus of control and health related behavior.
3. Differences in the choice of job search channel and in the probability of finding a job between immigrants and natives.
4. Why do low-educated workers invest less in further training?
5. Working hours mismatch and job mobility.
6. Gender differences in internal promotions.
Timetable:
Date |
Location |
|
Wednesday, 19.04.2017 14:00-16:00 |
HS IX |
Kick-Off (introduction, organizational issues, assigning topics) |
Monday, 19.06.2017 23:59 |
Deadline of submission of presentation slides and a of a preliminary draft of the seminar paper to sekretariat.schank@uni-mainz.de | |
Friday, 23.06.2017 09:00-18:00 |
HS V |
Presentations of seminar papers |
Sunday, 02.07.2017 23:59 |
Deadline of submission of the final seminar thesis to sekretariat.schank@uni-mainz.de (the printout can be submitted the next day at Pedelloge in the ReWi-1 building) |
Further information:
We will send before the first meeting an http-address where participants can state their preferences by ranking the topics from 1 to 6, but they can modify their preferences at the end of the first meeting. Topics will be assigned (according to the stated preferences) to groups of two or three students directly after the kick-off meeting. Students within groups can work together and also use a joint do-file in Stata. Group members should also present their results jointly. However, note that each person should write up her/his seminar thesis (not more than 18 pages including tables and figures but without references) independently.
We will supply the data-sets to be used. The main task for students is to investigate their research question empirically (based on the main reference provided) and to write up the results in a seminar paper.
Students need to submit an electronic version of their seminar thesis per e-mail to sekretariat.schank@uni-mainz.de, together with the literature cited in the thesis (except for the referenced provided by the chair), a Stata log-file and a do-file which produces all results reported in the seminar thesis. Students should make sure that the do-file runs through before submission and should also appropriately comment in the do-file which table etc. is produced by which command.
Further formal requirements will be discussed during the introductory meeting.
Contact:
Prof. Dr. Thorsten Schank (schank@uni-mainz.de)
Dr. Alexander Mosthaf (mosthaf@uni-mainz.de)
Master Seminar in Empirical Labor Economics (summer term 2016)
Further information including a description of the topics can be downloaded here.
Topic descriptions:
1. A natural experiment on sick pay cuts, sickness absence and labor costs
2. After work shopping? Employment effects of a deregulation of shop opening hours in the
German retail sector
3. The returns to cognitive abilities and personality traits in Germany
4. The impact of risk attitudes on entrepreneurial survival
5. Post-Unification Wage Growth in East Germany
6. Is soccer good for you? The motivational impact of big sporting events on the unemployed
Timetable:
Date |
Location |
|
Thursday, 21.04.2016 10:00-12:00 |
HS II |
Kick-Off (introduction, organizational issues, assigning topics) |
Tuesday, 14.06.2016 |
Submission of presentation slides and a preliminary draft of the seminar paper to sekretariat.schank@uni-mainz.de |
|
Thursday, 16.06.2016 09:25-17:45 |
Software Labor |
Presentations of seminar papers |
Until Sunday, 03.07.2016 23:59 |
Submission of the final seminar thesis to sekretariat.schank@uni-mainz.de (printout can be submitted the next day at the office of our chair) |
See Master Seminar winter term 2015/16 for further information.
Contact:
Prof. Dr. Thorsten Schank (schank@uni-mainz.de)
Dr. Alexander Mosthaf (mosthaf@uni-mainz.de)
Master Seminar in Empirical Labor Economics (winter term 2015/16)
Timetable:
Date | Location | |
Thursday,
29.10.2015
12:00 - 14:00
|
HS VI | Kick-Off (introduction, organizational issues, assigning topics) |
Thursday, 14.01.2016
09.00 - 16:00
|
03-125 (ReWi Neubau, Kleiner Dekanatssaal) |
Presentations of seminar papers |
By Sunday,
31.01.2016
10.00 – 18.00
|
Submission of the final seminar thesis to sekretariat.schank@uni-mainz.de (printout can be submitted the next day at the office of our chair) |
We will supply the data-sets to be used. The main task is to replicate, using Stata, (some of) the results and figures of the papers listed above and write them up in a seminar paper. Students should discuss the outline of their paper with Dr. Damir Stijepic.
Students need to submit an electronic version of their seminar thesis per e-mail to sekretariat.schank@uni-mainz.de, together with the literature cited in the thesis (except for the papers referenced above), a Stata log-file and do-file which produces all results reported in the seminar thesis. Students should make sure that the do-file runs through before submission and should also appropriately comment in the do-file table etc. is produced by which command.
Further formal requirements will be discussed during the introductory meeting.
|
In this semester we offer an applied seminar jointly with the Lufthansa AG. Based on real data supplied by Lufthansa, students will investigate various topics which are of direct relevance for the company’s market strategy.
All topics will be assigned to groups of two or three students directly after the kick-off meeting. Students can work together. Group members should also present their results jointly. However, note that each person should write up her/his seminar thesis independently.
Timetable:
Date | Location | |
Thursday,
08.05.2014
14.00 – 16.00
|
HS VI | Kick-Off (introduction, organizational issues, assigning topics) |
Friday, 27.06.2014
09.00 – 18.00
|
03-144 (Building SB II) |
Presentations of the (preliminarily) results |
Friday, 17.07.2014 | Submission of the final seminar thesis | |
Thursday,
24.07.2014
10.00 – 18.00
|
Frankfurt Airport | Presentation of the final results to staff of Lufthansa AG |
Topics:
- Impact of the new Premium Economy class
- Extrapolation of the market penetration
- Statistical Process Control (Alerting)
- Trend models
- Campaign History Report
- Determinants of Air Traffic to certain destinations