Improving accuracy by using information from relatives—The animal modelILRI
Presented by Raphael Mrode, ILRI, at the Australian Africa Universities (AAUN) Workshop on New Plant Breeding Methods for Sustainable Use of Genetic Resources and Security of Food Production, Mauritius University, Mauritius, 29-31 January 2018
Poisson distribution used in cases where the chance of any individual event being a success is very small. The distribution is used to describe the behavior of rare events.
It is limiting case of binomial distribution.
Improving accuracy by using information from relatives—The animal modelILRI
Presented by Raphael Mrode, ILRI, at the Australian Africa Universities (AAUN) Workshop on New Plant Breeding Methods for Sustainable Use of Genetic Resources and Security of Food Production, Mauritius University, Mauritius, 29-31 January 2018
Poisson distribution used in cases where the chance of any individual event being a success is very small. The distribution is used to describe the behavior of rare events.
It is limiting case of binomial distribution.
2024 State of Marketing Report – by HubspotMarius Sescu
https://www.hubspot.com/state-of-marketing
· Scaling relationships and proving ROI
· Social media is the place for search, sales, and service
· Authentic influencer partnerships fuel brand growth
· The strongest connections happen via call, click, chat, and camera.
· Time saved with AI leads to more creative work
· Seeking: A single source of truth
· TLDR; Get on social, try AI, and align your systems.
· More human marketing, powered by robots
ChatGPT is a revolutionary addition to the world since its introduction in 2022. A big shift in the sector of information gathering and processing happened because of this chatbot. What is the story of ChatGPT? How is the bot responding to prompts and generating contents? Swipe through these slides prepared by Expeed Software, a web development company regarding the development and technical intricacies of ChatGPT!
Product Design Trends in 2024 | Teenage EngineeringsPixeldarts
The realm of product design is a constantly changing environment where technology and style intersect. Every year introduces fresh challenges and exciting trends that mold the future of this captivating art form. In this piece, we delve into the significant trends set to influence the look and functionality of product design in the year 2024.
How Race, Age and Gender Shape Attitudes Towards Mental HealthThinkNow
Mental health has been in the news quite a bit lately. Dozens of U.S. states are currently suing Meta for contributing to the youth mental health crisis by inserting addictive features into their products, while the U.S. Surgeon General is touring the nation to bring awareness to the growing epidemic of loneliness and isolation. The country has endured periods of low national morale, such as in the 1970s when high inflation and the energy crisis worsened public sentiment following the Vietnam War. The current mood, however, feels different. Gallup recently reported that national mental health is at an all-time low, with few bright spots to lift spirits.
To better understand how Americans are feeling and their attitudes towards mental health in general, ThinkNow conducted a nationally representative quantitative survey of 1,500 respondents and found some interesting differences among ethnic, age and gender groups.
Technology
For example, 52% agree that technology and social media have a negative impact on mental health, but when broken out by race, 61% of Whites felt technology had a negative effect, and only 48% of Hispanics thought it did.
While technology has helped us keep in touch with friends and family in faraway places, it appears to have degraded our ability to connect in person. Staying connected online is a double-edged sword since the same news feed that brings us pictures of the grandkids and fluffy kittens also feeds us news about the wars in Israel and Ukraine, the dysfunction in Washington, the latest mass shooting and the climate crisis.
Hispanics may have a built-in defense against the isolation technology breeds, owing to their large, multigenerational households, strong social support systems, and tendency to use social media to stay connected with relatives abroad.
Age and Gender
When asked how individuals rate their mental health, men rate it higher than women by 11 percentage points, and Baby Boomers rank it highest at 83%, saying it’s good or excellent vs. 57% of Gen Z saying the same.
Gen Z spends the most amount of time on social media, so the notion that social media negatively affects mental health appears to be correlated. Unfortunately, Gen Z is also the generation that’s least comfortable discussing mental health concerns with healthcare professionals. Only 40% of them state they’re comfortable discussing their issues with a professional compared to 60% of Millennials and 65% of Boomers.
Race Affects Attitudes
As seen in previous research conducted by ThinkNow, Asian Americans lag other groups when it comes to awareness of mental health issues. Twenty-four percent of Asian Americans believe that having a mental health issue is a sign of weakness compared to the 16% average for all groups. Asians are also considerably less likely to be aware of mental health services in their communities (42% vs. 55%) and most likely to seek out information on social media (51% vs. 35%).
AI Trends in Creative Operations 2024 by Artwork Flow.pdfmarketingartwork
This article is all about what AI trends will emerge in the field of creative operations in 2024. All the marketers and brand builders should be aware of these trends for their further use and save themselves some time!
A report by thenetworkone and Kurio.
The contributing experts and agencies are (in an alphabetical order): Sylwia Rytel, Social Media Supervisor, 180heartbeats + JUNG v MATT (PL), Sharlene Jenner, Vice President - Director of Engagement Strategy, Abelson Taylor (USA), Alex Casanovas, Digital Director, Atrevia (ES), Dora Beilin, Senior Social Strategist, Barrett Hoffher (USA), Min Seo, Campaign Director, Brand New Agency (KR), Deshé M. Gully, Associate Strategist, Day One Agency (USA), Francesca Trevisan, Strategist, Different (IT), Trevor Crossman, CX and Digital Transformation Director; Olivia Hussey, Strategic Planner; Simi Srinarula, Social Media Manager, The Hallway (AUS), James Hebbert, Managing Director, Hylink (CN / UK), Mundy Álvarez, Planning Director; Pedro Rojas, Social Media Manager; Pancho González, CCO, Inbrax (CH), Oana Oprea, Head of Digital Planning, Jam Session Agency (RO), Amy Bottrill, Social Account Director, Launch (UK), Gaby Arriaga, Founder, Leonardo1452 (MX), Shantesh S Row, Creative Director, Liwa (UAE), Rajesh Mehta, Chief Strategy Officer; Dhruv Gaur, Digital Planning Lead; Leonie Mergulhao, Account Supervisor - Social Media & PR, Medulla (IN), Aurelija Plioplytė, Head of Digital & Social, Not Perfect (LI), Daiana Khaidargaliyeva, Account Manager, Osaka Labs (UK / USA), Stefanie Söhnchen, Vice President Digital, PIABO Communications (DE), Elisabeth Winiartati, Managing Consultant, Head of Global Integrated Communications; Lydia Aprina, Account Manager, Integrated Marketing and Communications; Nita Prabowo, Account Manager, Integrated Marketing and Communications; Okhi, Web Developer, PNTR Group (ID), Kei Obusan, Insights Director; Daffi Ranandi, Insights Manager, Radarr (SG), Gautam Reghunath, Co-founder & CEO, Talented (IN), Donagh Humphreys, Head of Social and Digital Innovation, THINKHOUSE (IRE), Sarah Yim, Strategy Director, Zulu Alpha Kilo (CA).
Trends In Paid Search: Navigating The Digital Landscape In 2024Search Engine Journal
The search marketing landscape is evolving rapidly with new technologies, and professionals, like you, rely on innovative paid search strategies to meet changing demands.
It’s important that you’re ready to implement new strategies in 2024.
Check this out and learn the top trends in paid search advertising that are expected to gain traction, so you can drive higher ROI more efficiently in 2024.
You’ll learn:
- The latest trends in AI and automation, and what this means for an evolving paid search ecosystem.
- New developments in privacy and data regulation.
- Emerging ad formats that are expected to make an impact next year.
Watch Sreekant Lanka from iQuanti and Irina Klein from OneMain Financial as they dive into the future of paid search and explore the trends, strategies, and technologies that will shape the search marketing landscape.
If you’re looking to assess your paid search strategy and design an industry-aligned plan for 2024, then this webinar is for you.
5 Public speaking tips from TED - Visualized summarySpeakerHub
From their humble beginnings in 1984, TED has grown into the world’s most powerful amplifier for speakers and thought-leaders to share their ideas. They have over 2,400 filmed talks (not including the 30,000+ TEDx videos) freely available online, and have hosted over 17,500 events around the world.
With over one billion views in a year, it’s no wonder that so many speakers are looking to TED for ideas on how to share their message more effectively.
The article “5 Public-Speaking Tips TED Gives Its Speakers”, by Carmine Gallo for Forbes, gives speakers five practical ways to connect with their audience, and effectively share their ideas on stage.
Whether you are gearing up to get on a TED stage yourself, or just want to master the skills that so many of their speakers possess, these tips and quotes from Chris Anderson, the TED Talks Curator, will encourage you to make the most impactful impression on your audience.
See the full article and more summaries like this on SpeakerHub here: https://speakerhub.com/blog/5-presentation-tips-ted-gives-its-speakers
See the original article on Forbes here:
http://www.forbes.com/forbes/welcome/?toURL=http://www.forbes.com/sites/carminegallo/2016/05/06/5-public-speaking-tips-ted-gives-its-speakers/&refURL=&referrer=#5c07a8221d9b
ChatGPT and the Future of Work - Clark Boyd Clark Boyd
Everyone is in agreement that ChatGPT (and other generative AI tools) will shape the future of work. Yet there is little consensus on exactly how, when, and to what extent this technology will change our world.
Businesses that extract maximum value from ChatGPT will use it as a collaborative tool for everything from brainstorming to technical maintenance.
For individuals, now is the time to pinpoint the skills the future professional will need to thrive in the AI age.
Check out this presentation to understand what ChatGPT is, how it will shape the future of work, and how you can prepare to take advantage.
A brief introduction to DataScience with explaining of the concepts, algorithms, machine learning, supervised and unsupervised learning, clustering, statistics, data preprocessing, real-world applications etc.
It's part of a Data Science Corner Campaign where I will be discussing the fundamentals of DataScience, AIML, Statistics etc.
Time Management & Productivity - Best PracticesVit Horky
Here's my presentation on by proven best practices how to manage your work time effectively and how to improve your productivity. It includes practical tips and how to use tools such as Slack, Google Apps, Hubspot, Google Calendar, Gmail and others.
The six step guide to practical project managementMindGenius
The six step guide to practical project management
If you think managing projects is too difficult, think again.
We’ve stripped back project management processes to the
basics – to make it quicker and easier, without sacrificing
the vital ingredients for success.
“If you’re looking for some real-world guidance, then The Six Step Guide to Practical Project Management will help.”
Dr Andrew Makar, Tactical Project Management
2024 State of Marketing Report – by HubspotMarius Sescu
https://www.hubspot.com/state-of-marketing
· Scaling relationships and proving ROI
· Social media is the place for search, sales, and service
· Authentic influencer partnerships fuel brand growth
· The strongest connections happen via call, click, chat, and camera.
· Time saved with AI leads to more creative work
· Seeking: A single source of truth
· TLDR; Get on social, try AI, and align your systems.
· More human marketing, powered by robots
ChatGPT is a revolutionary addition to the world since its introduction in 2022. A big shift in the sector of information gathering and processing happened because of this chatbot. What is the story of ChatGPT? How is the bot responding to prompts and generating contents? Swipe through these slides prepared by Expeed Software, a web development company regarding the development and technical intricacies of ChatGPT!
Product Design Trends in 2024 | Teenage EngineeringsPixeldarts
The realm of product design is a constantly changing environment where technology and style intersect. Every year introduces fresh challenges and exciting trends that mold the future of this captivating art form. In this piece, we delve into the significant trends set to influence the look and functionality of product design in the year 2024.
How Race, Age and Gender Shape Attitudes Towards Mental HealthThinkNow
Mental health has been in the news quite a bit lately. Dozens of U.S. states are currently suing Meta for contributing to the youth mental health crisis by inserting addictive features into their products, while the U.S. Surgeon General is touring the nation to bring awareness to the growing epidemic of loneliness and isolation. The country has endured periods of low national morale, such as in the 1970s when high inflation and the energy crisis worsened public sentiment following the Vietnam War. The current mood, however, feels different. Gallup recently reported that national mental health is at an all-time low, with few bright spots to lift spirits.
To better understand how Americans are feeling and their attitudes towards mental health in general, ThinkNow conducted a nationally representative quantitative survey of 1,500 respondents and found some interesting differences among ethnic, age and gender groups.
Technology
For example, 52% agree that technology and social media have a negative impact on mental health, but when broken out by race, 61% of Whites felt technology had a negative effect, and only 48% of Hispanics thought it did.
While technology has helped us keep in touch with friends and family in faraway places, it appears to have degraded our ability to connect in person. Staying connected online is a double-edged sword since the same news feed that brings us pictures of the grandkids and fluffy kittens also feeds us news about the wars in Israel and Ukraine, the dysfunction in Washington, the latest mass shooting and the climate crisis.
Hispanics may have a built-in defense against the isolation technology breeds, owing to their large, multigenerational households, strong social support systems, and tendency to use social media to stay connected with relatives abroad.
Age and Gender
When asked how individuals rate their mental health, men rate it higher than women by 11 percentage points, and Baby Boomers rank it highest at 83%, saying it’s good or excellent vs. 57% of Gen Z saying the same.
Gen Z spends the most amount of time on social media, so the notion that social media negatively affects mental health appears to be correlated. Unfortunately, Gen Z is also the generation that’s least comfortable discussing mental health concerns with healthcare professionals. Only 40% of them state they’re comfortable discussing their issues with a professional compared to 60% of Millennials and 65% of Boomers.
Race Affects Attitudes
As seen in previous research conducted by ThinkNow, Asian Americans lag other groups when it comes to awareness of mental health issues. Twenty-four percent of Asian Americans believe that having a mental health issue is a sign of weakness compared to the 16% average for all groups. Asians are also considerably less likely to be aware of mental health services in their communities (42% vs. 55%) and most likely to seek out information on social media (51% vs. 35%).
AI Trends in Creative Operations 2024 by Artwork Flow.pdfmarketingartwork
This article is all about what AI trends will emerge in the field of creative operations in 2024. All the marketers and brand builders should be aware of these trends for their further use and save themselves some time!
A report by thenetworkone and Kurio.
The contributing experts and agencies are (in an alphabetical order): Sylwia Rytel, Social Media Supervisor, 180heartbeats + JUNG v MATT (PL), Sharlene Jenner, Vice President - Director of Engagement Strategy, Abelson Taylor (USA), Alex Casanovas, Digital Director, Atrevia (ES), Dora Beilin, Senior Social Strategist, Barrett Hoffher (USA), Min Seo, Campaign Director, Brand New Agency (KR), Deshé M. Gully, Associate Strategist, Day One Agency (USA), Francesca Trevisan, Strategist, Different (IT), Trevor Crossman, CX and Digital Transformation Director; Olivia Hussey, Strategic Planner; Simi Srinarula, Social Media Manager, The Hallway (AUS), James Hebbert, Managing Director, Hylink (CN / UK), Mundy Álvarez, Planning Director; Pedro Rojas, Social Media Manager; Pancho González, CCO, Inbrax (CH), Oana Oprea, Head of Digital Planning, Jam Session Agency (RO), Amy Bottrill, Social Account Director, Launch (UK), Gaby Arriaga, Founder, Leonardo1452 (MX), Shantesh S Row, Creative Director, Liwa (UAE), Rajesh Mehta, Chief Strategy Officer; Dhruv Gaur, Digital Planning Lead; Leonie Mergulhao, Account Supervisor - Social Media & PR, Medulla (IN), Aurelija Plioplytė, Head of Digital & Social, Not Perfect (LI), Daiana Khaidargaliyeva, Account Manager, Osaka Labs (UK / USA), Stefanie Söhnchen, Vice President Digital, PIABO Communications (DE), Elisabeth Winiartati, Managing Consultant, Head of Global Integrated Communications; Lydia Aprina, Account Manager, Integrated Marketing and Communications; Nita Prabowo, Account Manager, Integrated Marketing and Communications; Okhi, Web Developer, PNTR Group (ID), Kei Obusan, Insights Director; Daffi Ranandi, Insights Manager, Radarr (SG), Gautam Reghunath, Co-founder & CEO, Talented (IN), Donagh Humphreys, Head of Social and Digital Innovation, THINKHOUSE (IRE), Sarah Yim, Strategy Director, Zulu Alpha Kilo (CA).
Trends In Paid Search: Navigating The Digital Landscape In 2024Search Engine Journal
The search marketing landscape is evolving rapidly with new technologies, and professionals, like you, rely on innovative paid search strategies to meet changing demands.
It’s important that you’re ready to implement new strategies in 2024.
Check this out and learn the top trends in paid search advertising that are expected to gain traction, so you can drive higher ROI more efficiently in 2024.
You’ll learn:
- The latest trends in AI and automation, and what this means for an evolving paid search ecosystem.
- New developments in privacy and data regulation.
- Emerging ad formats that are expected to make an impact next year.
Watch Sreekant Lanka from iQuanti and Irina Klein from OneMain Financial as they dive into the future of paid search and explore the trends, strategies, and technologies that will shape the search marketing landscape.
If you’re looking to assess your paid search strategy and design an industry-aligned plan for 2024, then this webinar is for you.
5 Public speaking tips from TED - Visualized summarySpeakerHub
From their humble beginnings in 1984, TED has grown into the world’s most powerful amplifier for speakers and thought-leaders to share their ideas. They have over 2,400 filmed talks (not including the 30,000+ TEDx videos) freely available online, and have hosted over 17,500 events around the world.
With over one billion views in a year, it’s no wonder that so many speakers are looking to TED for ideas on how to share their message more effectively.
The article “5 Public-Speaking Tips TED Gives Its Speakers”, by Carmine Gallo for Forbes, gives speakers five practical ways to connect with their audience, and effectively share their ideas on stage.
Whether you are gearing up to get on a TED stage yourself, or just want to master the skills that so many of their speakers possess, these tips and quotes from Chris Anderson, the TED Talks Curator, will encourage you to make the most impactful impression on your audience.
See the full article and more summaries like this on SpeakerHub here: https://speakerhub.com/blog/5-presentation-tips-ted-gives-its-speakers
See the original article on Forbes here:
http://www.forbes.com/forbes/welcome/?toURL=http://www.forbes.com/sites/carminegallo/2016/05/06/5-public-speaking-tips-ted-gives-its-speakers/&refURL=&referrer=#5c07a8221d9b
ChatGPT and the Future of Work - Clark Boyd Clark Boyd
Everyone is in agreement that ChatGPT (and other generative AI tools) will shape the future of work. Yet there is little consensus on exactly how, when, and to what extent this technology will change our world.
Businesses that extract maximum value from ChatGPT will use it as a collaborative tool for everything from brainstorming to technical maintenance.
For individuals, now is the time to pinpoint the skills the future professional will need to thrive in the AI age.
Check out this presentation to understand what ChatGPT is, how it will shape the future of work, and how you can prepare to take advantage.
A brief introduction to DataScience with explaining of the concepts, algorithms, machine learning, supervised and unsupervised learning, clustering, statistics, data preprocessing, real-world applications etc.
It's part of a Data Science Corner Campaign where I will be discussing the fundamentals of DataScience, AIML, Statistics etc.
Time Management & Productivity - Best PracticesVit Horky
Here's my presentation on by proven best practices how to manage your work time effectively and how to improve your productivity. It includes practical tips and how to use tools such as Slack, Google Apps, Hubspot, Google Calendar, Gmail and others.
The six step guide to practical project managementMindGenius
The six step guide to practical project management
If you think managing projects is too difficult, think again.
We’ve stripped back project management processes to the
basics – to make it quicker and easier, without sacrificing
the vital ingredients for success.
“If you’re looking for some real-world guidance, then The Six Step Guide to Practical Project Management will help.”
Dr Andrew Makar, Tactical Project Management
Beginners Guide to TikTok for Search - Rachel Pearson - We are Tilt __ Bright...
Sommen van toevalsvariabelen en de Centrale Limietstelling
1. Deel II : Kansrekenen
en toevalsvariabelen
Hoofdstuk 3 : Sommen van
onafhankelijke toevalsvariabelen
2. Inhoud
1. Onafhankelijkheid en correlatie
2. Verwachtingswaarde en variantie
3. Verdeling van sommen van onafhankelijke
toevalsvariabelen (Centrale Limietstelling)
3. Inhoud
1. Onafhankelijkheid en correlatie
2. Verwachtingswaarde en variantie
3. Verdeling van sommen van onafhankelijke
toevalsvariabelen (Centrale Limietstelling)
4. Onafhankelijke t.v.
• Herinner dat de gebeurtenissen A en B
onafhankelijk zijn als en slechts als
P(A en B) = P(A) ∙ P(B)
• Twee toevalsvariabelen X en Y zijn onafhankelijk,
als elke gebeurtenis waarbij alleen X betrokken is
onafhankelijk is van elke gebeurtenis waarbij
alleen Y betrokken is.
5. Paarsgewijs onafhankelijk
• De toevalsvariabelen X1, X2, …, Xn zijn
paarsgewijs (of onderling) onafhankelijk als en
slechts als elk paar toevalsvariabelen Xi en Xj (i≠j)
onafhankelijk is.
6. Correlatie : definitie
• Correlatie tussen twee toevalsvariabelen
X en Y = r = maat voor de richting en de
sterkte van de lineaire samenhang tussen
X en Y
X X Y Y
r E
Y
X
7. Correlatie : eigenschappen (1)
• ─1 ≤ r ≤ 1
• De correlatie is dimensieloos
• Het teken van de correlatie geeft aan of X en Y
positief (in dezelfde zin) of negatief (in
tegengestelde zin) met elkaar verbonden zijn.
• De grootte van de correlatie geeft de sterkte van
de lineaire samenhang.
8. Correlatie : eigenschappen (2)
• Als r = 0, dan is er totaal geen lineair verband
tussen X en Y (X en Y zijn ongecorreleerd)
• Als r = 1 (resp. ─1) dan is er een perfecte
positieve (resp. negatieve) lineaire samenhang
tussen X en Y :
Y = a + b X met b > 0 (resp. < 0)
• Hoe dichter r bij 1 ligt, hoe sterker de lineaire
samenhang. Hoe dichter bij 0, hoe zwakker.
9. Ongecorreleerd versus onafhankelijk
• Als X en Y onafhankelijk zijn, dan zijn ze ook
ongecorreleerd.
• Het omgekeerde is niet waar!!
Onafhankelijk
Ongecorreleerd
10. Inhoud
1. Onafhankelijkheid en correlatie
2. Verwachtingswaarde en variantie
a)
b)
Verwachtingswaarde en variantie van een lineaire
combinatie
Verwachtingswaarde en variantie van een
steekproefgemiddelde (en een som)
3. Verdeling van sommen van onafhankelijke
toevalsvariabelen (Centrale Limietstelling)
11. Lineaire combinaties
• Voorbeeld: we gooien 3 keer met een dobbelsteen
en noteren met X het aantal keer dat je 6 gegooid
hebt bij die 3 worpen en met Y het aantal keer dat
je geen 6 gegooid hebt bij diezelfde 3 worpen.
Dan zal X = 0.5 , Y = 2.5 en X² = Y² = 5/12.
• Wat is X+Y ? ²X+Y ?
12. Algemeen
• Er geldt steeds dat X+Y = X + Y
• Er geldt echter niet steeds dat
²X+Y = ²X + ²Y !
13. Algemeen : lineaire combinaties
X Y X Y
2
X Y
2
X
2
Y
2 r XY
Uitbreiding:
aX bY a X b Y
2
aX bY
a
2
2
X
b
2
2
Y
2a b r XY
15. Voorbeeld : verschil
• Neem a = 1 en b = -1:
X Y X Y
2
X Y
2
X
2
Y
2 r XY
• Voor onafhankelijke toevalsvariabelen:
2
X Y
2
X
2
Y
16. Oefening 1
Meneer Goedhart verkoopt kaarsen en wenskaarten voor
Amnesty International. Een set kaarsen kost 7 € en een
pakje wenskaarten kost 10 €. Op basis van voorgaande
jaren weet meneer Goedhart dat er gemiddeld per week
100 sets kaarsen en 150 pakjes wenskaarten verkocht
worden, met een standaardafwijking van respectievelijk 20
en 25. Het aantal verkochte kaarsen per week is
onafhankelijk van het aantal verkochte wenskaarten. Wat
zijn de verwachte totale inkomsten per week? En met
welke standaardafwijking?
17. Oefening 2
Veronderstel dat X (resp. Y) de maandelijkse return is voor
het aandeel Dell (resp. Apple). Op basis van maandelijkse
returns tussen 1990 en 2008, weten we dat X = 2.02%, X
= 16.59%, Y = 1.75%, Y = 15.09%. De correlatie tussen
X en Y bedraagt r = 0.379. Sandra heeft in haar
portefeuille 60% aandelen Dell en 40% aandelen Apple,
dus de maandelijkse return voor haar portefeuille is de
toevalsvariabele
R = 0.6 X + 0.4 Y.
Wat is de verwachte return en de standaardafwijking van
Sandra’s portefeuille.
18. Inhoud
1. Onafhankelijkheid en correlatie
2. Verwachtingswaarde en variantie
a)
b)
Verwachtingswaarde en variantie van een lineaire
combinatie
Verwachtingswaarde en variantie van een
steekproefgemiddelde (en een som)
3. Verdeling van sommen van onafhankelijke
toevalsvariabelen (Centrale Limietstelling)
19. Populatie versus steekproef
Populatie = ALLE HUBstudenten
= gemiddeld IQ van
ALLE HUB-studenten
= populatiegemiddelde
Constante
Schatting voor
23. Steekproefgemiddelde : algemeen
• We wensen de verwachting van een t.v. X te
schatten.
• We nemen een steekproef van omvang n uit X, dit
betekent :
o X1, X2,…, Xn onderling onafhankelijk
o X1, X2,…, Xn allen verdeeld zoals X
• Steekproefgemiddelde:
X
1
n
X
n
i 1
i
1
n
X 1
X2 Xn
25. Verwachte waarde
• Som
E(Sn) = E(X1 + X2 + … + Xn)
= E(X1) + E(X2) + … + E(Xn)
Alle Xi
verdeeld
=++…+
zoals X
=n
• Steekproefgemiddelde
E(X ) E(
Sn
n
)
1
n
E (Sn )
1
n
n
27. X1, …, Xn
onderling
onafhankelijk
Variantie
Alle Xi verdeeld
zoals X
• Som
Var(Sn) = Var(X1 + X2 + … + Xn)
= Var(X1) + Var(X2) + … + Var(Xn)
= ² + ² + … + ²
= n ²
• Steekproefgemiddelde
Var ( X ) Var (
Sn
n
)
1
n
2
Var ( S n )
1
n
2
n
2
2
n
29. Inhoud
1. Onafhankelijkheid en correlatie
2. Verwachtingswaarde en variantie
3. Verdeling van sommen van onafhankelijke
toevalsvariabelen (Centrale Limietstelling)
31. Verdeling
• Het vorige is in feite een speciaal geval van de
volgende eigenschap:
• Als X en Y normaal verdeeld zijn en onafhankelijk,
dan is elke lineaire combinatie
aX+bY
ook normaal verdeeld.
33. Toepassing : Normale benadering
van de binomiale verdeling
• X ~ Be(p)
X = p, ²X = p (1−p)
• Steekproef X1, X2, …, Xn
• Sn = X1 + X2 + … + Xn = aantal successen
• Dan geldt
Sn ~ Bi(n, p)
• En wegens de Centrale Limietstelling
S n N (n p ,
n p (1 p ) )
34. Stelling van de Moivre-Laplace
X ~ Bi n , p
Y ~ N n p , n p 1 p
35. Oefening
Je gooit 20 keer met een zuiver muntstuk. Bereken
zowel exact via de Binomiale verdeling als met
de Normale benadering:
a) Kans op minstens 12 keer kop?
b) Kans op minstens 5 en hoogstens 11 keer kop?
c) Kans op juist 7 keer kop?
d) Kans op minder dan 9 keer kop?
37. X ~ B i(2 0 ,0 .5 ) b e n a d e rd d o o r Y ~ N (1 0 , v (5 ))
0 ,2
0 ,1 8
0 ,1 6
0 ,1 4
p (x )
0 ,1 2
0 ,1
0 ,0 8
P(X≥12)
0 ,0 6
0 ,0 4
0 ,0 2
0
0
1
2
3
4
5
6
7
8
9
10
x
11
12
13
14
15
16
17
18
19
20
38. X ~ B i(2 0 ,0 .5 ) b e n a d e rd d o o r Y ~ N (1 0 , v (5 ))
0 ,2
0 ,1 8
0 ,1 6
0 ,1 4
p (x )
0 ,1 2
0 ,1
0 ,0 8
P(Y≥12)
0 ,0 6
0 ,0 4
0 ,0 2
0
0
1
2
3
4
5
6
7
8
9
10
x
11
12
13
14
15
16
17
18
19
20
39. X ~ B i(2 0 ,0 .5 ) b e n a d e rd d o o r Y ~ N (1 0 , v (5 ))
0 ,2
0 ,1 8
0 ,1 6
0 ,1 4
p (x )
0 ,1 2
0 ,1
0 ,0 8
P(Y≥11,5)
0 ,0 6
0 ,0 4
0 ,0 2
0
0
1
2
3
4
5
6
7
8
9
10
x
11
12
13
14
15
16
17
18
19
20