शैडोइंग अभ्यास: Statistical Thinking in Science: Crash Course Scientific Thinking #2 - वीडियो के साथ अंग्रेजी बोलना सीखें

I am going to die, eventually.

Which is pretty important to me personally, so I'd like to know roughly at what age I am most likely to die.

You might guess something like 70, which, based on a national dataset,

was the average age of death in the US for men who died between 2018 and 2023.

But it might be that 79 is the more accurate answer, which is an extra 9 years.

So how can I make sure I'm using the best number to answer my question?

stats really tell me when I might die?

And is there a way to look at these numbers and not have an existential crisis?

Hi, I'm Hank Green, and this is Crash Course Scientific Thinking.

Do not worry, I'm not going to teach you how to do statistics today.

We have a whole other course about that.

What we're talking about here is how to make sense of the stats you encounter in your everyday life.

Statistics are vital for so much of what goes on around us, from designing video games to creating impactful government health policies.

But statistics can be misleading.

It's not because the numbers are lying.

It's that if we don't understand how the numbers are being used, we might get the wrong impression about their meaning.

Scientists use statistics to understand data, but when they're looking at those numbers, they have all of the context that goes along with them.

By the time these stats are reported on in the news, they often lose some of that context.

Which can have big impacts on the ways that we see the world as consumers of science news.

Scientists rely on numbers to build knowledge.

But since they can't measure every person, they use samples.

Smaller groups they can measure to better understand a larger group.

Which means there's always some uncertainty.

So while stats could never tell me, Hank Green, exactly when I will die, they can tell me when a person like me is most likely to die.

So what is the typical age of death for an American man?

Well, when it comes to statistics, there's a few different ways of determining what's typical.

One of the most common is to find the mean, or average, the sum of all the numbers in a sample divided by how many numbers are in that sample.

That's where we get the first number from.

Based on a large sample of residents who died between 2018 and 2023, the average or mean age of death of a man in the US is 70.

But that mean is dragged down by people who died way younger than 70, even though there are fewer of them.

So maybe I don't actually want the average.

Maybe instead I want to know the most common age of death, or the mode.

That answer is actually way different from the mean.

The mode is the number that shows up the most in the data, which is where we get 79 from.

But actually, most of the numbers in the sample are to the left of the mode, so it's actually more likely that I'd land on one of the numbers under 79 than

that I'd land squarely on or after 79.

So say then I want to find an age somewhat close to the average age when someone like me would die.

I can look at the numbers in the graph and find the standard deviation, which tells me how spread out the other points in the sample are from the mean,

which in turn can help me figure out how typical that number really is.

If the standard deviation is small, that tells me most people in the sample are dying at ages pretty close to the average age.

Another number that might be helpful is the median, or the point right in the middle of the group, where an equal number of US men die before and after.

And that would be 73, still relatively close to 70 and 79, but different enough to matter.

Because the median is always the number directly in the middle of the dataset, it is less likely to be skewed one way or the other the way a mean might be.

So it might tell me way more about when American men tend to die.

Though of course, it still cannot tell me when I'll die.

The point is, averages like mean, median, and mode are different ways of telling you what might be typical.

But they're way more useful when you understand how each one operates differently.

And they're even more useful when combined with the standard deviation, which tells us how typical typical really is.

There's always a degree of uncertainty when it comes to statistics.

So another useful question is, okay, but how certain are we of these stats?

For a stat to really mean anything, I need to know how much confidence to have in it.

How likely is it that if I ran the numbers again, I'd get those same results?

For that, I'd need to calculate a confidence interval, or a range of numbers that I can expect a result to fall within a certain percentage of the time.

A 95% confidence interval means that if scientists repeated the study 100 times with new samples,

the statistic they're measuring would fall in that range about 95 times.

It shows how much that number might vary and how much trust can be put into it.

A stat with a high confidence interval is quite predictive, but it is not perfect.

So when encountering statistics in the real world, it's good to remember that every stat actually has two pieces.

First, the number.

And second, how precisely scientists know that number.

And it is way better to be roughly right than precisely wrong.

Hold on for a moment, I'm being told that we have a special guest on the way.

It sounds like it's time for some sage advice.

Hi, Hank.

Did you know that women also die?

Yes, I did sadly know that.

Well, you should talk about dudes a lot.

For example, consider this updated birth control pill.

According to the news, it raised the risk of developing deadly blood clots by 100 percent!

That's definitely a big statistic.

It sounds like it, right?

With the old pill, one in 7,000 people were at risk of developing blood clots.

With the new pill, the risk doubled.

Do you know what it became?

Yeah, if it doubled, I guess it went from one to two.

What a great guess!

It sounds like a lot when someone says risk has increased by 100%, but that's just what scientists call the relative risk,

or how much the likelihood of something happening gets bigger or smaller relative to something else.

Which can be helpful to know, but it doesn't tell us the whole story.

For that, we need the absolute risk, or the number of people actually experiencing an event in relation to the population at risk.

The absolute risk stayed relatively low.

Right?

It increased to 2 in 7,000.

Still important, but people need that context you talked about earlier to make informed decisions.

At the time, though, a lot of people only learned about this risk in relative terms through the news.

So people switched to less effective pregnancy prevention methods.

And you know what poses a higher risk of life-threatening blood clots than the birth control pill?

Pregnancy!

So the more we understand numbers in context, the better we'll be at making informed decisions for our lives.

And that's been today's Sage Advice.

Thanks, Sage.

Sage is correct.

Understanding the difference between absolute risk and relative risk can help us make sense of

so many of the stats we encounter in our daily lives.

Like, how great is my risk of developing cancer if I go to the beach every day and don't wear sunscreen?

Which actually brings me to my next point.

Scientists often analyze relationships in data, like the relationship between sunscreen and skin cancer.

These are known as correlations.

A correlation is a relationship between two or more variables, which are basically anything that can be measured or counted.

100

A correlation between two variables can be loose or it can be tight, which we quantify with their r-value.

101

It's a number from negative one to one that shows how tightly two things move together.

102

One means a perfect match, negative one means perfect opposite, and zero means no connection.

103

The simplest kind of correlation is linear between just two variables.

104

A correlation can be negative, meaning one variable gets smaller as the other gets bigger.

105

Like, for example, how higher rates of wearing sunscreen correlate to lower rates of skin cancer.

106

Or it can be positive, like if, say, higher rates of ice cream sales correlate to higher rates of shark attacks.

107

You might have heard the saying, correlation doesn't equal causation.

108

But there's actually more to it than that.

109

Like in the case of sunscreen, there's a lot of good evidence that wearing it really does lower the risk of cancer.

110

There is a causal link in the correlation.

111

But in the case of shark attacks, it's safe to say that the ice cream isn't causing them.

112

Warm weather is indirectly leading to both.

113

In this case, weather is a confounding variable, or a factor that influences the outcome of a study without being controlled for.

114

These can blur what's actually going on in the data if scientists don't measure and account for them.

115

For example, some studies have shown a positive correlation between personal health and visits to the beach.

116

But it's hard to know if beaches make people healthier, if healthy people are more likely to go to the beach, or if there's some third confounding variable,

117

like the level of wealth, that results in both better health and more beach visits.

118

And even if scientists do a good job of controlling for all these variables, they still have to ask, is it possible this result was just a fluke in our data?

119

In other words, was it statistically significant?

120

Statistical significance means the result is strong enough that it would be surprising to get by random chance.

121

But don't let this phrasing mislead you either.

122

In science, significant doesn't mean important.

123

Like how I say, Doritos are a significant part of my life.

124

That means they're important to me.

125

But that's different from statistical significance.

126

Total significance doesn't even necessarily mean meaningful in the real world.

127

It's more like, it would be surprising to get this result at random, so we should dig deeper.

128

And digging deeper is something we can all do when it comes to statistics.

129

And that begins by understanding that there will always be some uncertainty.

130

Scientists can't possibly measure every version of everything they want to study.

131

But stats can help them measure the uncertainty.

132

And understanding what numbers can and can't tell us about ourselves, each other, and the world can help us not only better understand the way that science works,

133

but also help us make more informed judgments about our own lives. In our next episode,

134

we're going to look at how rare it actually is for a single experiment to change our understanding of science.

135

I'll see you then.

136

This episode of Crash Course Scientific Thinking was produced in partnership with HHMI Bio interactive, bringing real science stories to thousands of high school and undergrad life science classrooms.

137

If you're a teacher, visit their website for resources that explore the topics we discussed in this video today.

138

Thank you.

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इस पाठ की शब्दावली और बोलने के सुझाव

इस वीडियो में शैडोइंग के लिए 138 वाक्य और 1934 शब्द हैं। बोला गया हिस्सा 11:01 लंबा है। वक्ता लगभग 175 शब्द प्रति मिनट की स्वाभाविक गति से बोलता है, जो रोज़मर्रा की बातचीत के करीब है। 87% शब्द अंग्रेज़ी के 3,000 सबसे आम शब्दों में से हैं; बाकी शब्द अभ्यास से पहले देख लेना अच्छा रहेगा।

इस वीडियो की मुख्य शब्दावली

वीडियो के 15 सीखने लायक शब्द, उच्चारण और अर्थ के साथ:

शब्द	उच्चारण	अर्थ
scientist संज्ञा	/ˈsaɪəntəst/	वैज्ञानिक, आलिम
correlation संज्ञा	/ˌkɔɹ.əˈleɪ.ʃən/	सहसंबंध
relative संज्ञा	/ˈɹɛl.ə.tɪv/	रिश्तेदार, नातेदार
pill संज्ञा	/pɪl/	गोली, गुटिका
uncertainty संज्ञा	/ʌnˈsɜːtənti/	संदेह, संशय
encounter क्रिया	/ɪnˈkaʊntɚ/	सामना, भेंट
inform क्रिया	/ɪnˈfɔɹm/	सूचित करना, बताना
interval संज्ञा	/ˈɪntɚvəl/	अंतराल
helpful विशेषण	/ˈhɛlp.fl̩/	मददगार
pregnancy संज्ञा	/ˈpɹɛɡnənsi/	गर्भावस्था
precisely क्रिया विशेषण	/pɹɪˈsaɪs.li/	यथार्थतः, यथावत्
topic संज्ञा	/ˈtɑpɪk/	प्रसंग, विषय
necessarily क्रिया विशेषण	/ˌnɛs.əˈsɛɹ.ə.li/	अवश्य, अनिवार्यतः
partnership संज्ञा	/ˈpɑɹtnɚʃɪp/	भागीदारी
percentage संज्ञा	/pə(ɹ)ˈsɛntɪd͡ʒ/	प्रतिशतता

ध्यान देने योग्य उच्चारण

वक्ता 33 बार संक्षिप्त रूपों का प्रयोग करता है, जैसे don't, I'd, they're। इन्हें वैसे ही छोटा बोलें जैसा आप सुनते हैं।

“sh” और “zh” की ध्वनियाँ: correlation /ˌkɔɹ.əˈleɪ.ʃən/, partnership /ˈpɑɹtnɚʃɪp/, impression /ɪmˈpɹɛʃn̩/, relation /ɹɪˈleɪʃ(ə)n/, prevention /pɹɪˈvɛnʃən/
लंबे शब्द — बलाघात सही रखें: correlation /ˌkɔɹ.əˈleɪ.ʃən/, statistical /stəˈtɪs.tɪ.kəl/, uncertainty /ʌnˈsɜːtənti/, significance /sɪɡˈnɪfɪkəns/, necessarily /ˌnɛs.əˈsɛɹ.ə.li/

इस वीडियो से अभ्यास कैसे करें

पहले बिना बोले पूरा वीडियो एक बार सुनें और जो शब्द नहीं आते उन्हें लिख लें।
0.75× गति से शुरू करें, एक-एक वाक्य की शैडोइंग करें, और सहज लगने पर सामान्य गति पर लौटें।
अपनी आवाज़ रिकॉर्ड करें और मूल से तुलना करें, ख़ासकर scientist, correlation, relative जैसे शब्दों पर ध्यान दें।

इस वीडियो का व्याकरण

वक्ता जिन संरचनाओं का सबसे अधिक प्रयोग करता है, वीडियो के असली शब्दों के साथ:

संरचना	वीडियो में
Passive voice be + past participle — ज़ोर इस पर कि क्या होता है, न कि कौन करता है	are reported · is dragged · be skewed
Relative clauses who / which + उपवाक्य — व्यक्ति या वस्तु के बारे में अतिरिक्त जानकारी	men who died · answer, which is · people who died
Present perfect have/has + past participle — बीता हुआ काम जिसका असर अभी भी है	has increased · have shown

शैडोइंग तकनीक क्या है?

शैडोइंग (Shadowing) एक विज्ञान-समर्थित भाषा सीखने की तकनीक है जो मूल रूप से पेशेवर दुभाषिया प्रशिक्षण के लिए विकसित की गई थी। विधि सरल लेकिन शक्तिशाली है: आप मूल अंग्रेज़ी ऑडियो सुनते हैं और तुरंत इसे ज़ोर से दोहराते हैं — जैसे वक्ता की छाया 1-2 सेकंड की देरी से। शोध से पता चलता है कि यह उच्चारण सटीकता, स्वर, लय, जुड़ी हुई ध्वनियाँ, सुनने की समझ और बोलने की प्रवाहशीलता में काफ़ी सुधार करता है।

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इस पाठ की शब्दावली और बोलने के सुझाव

इस वीडियो की मुख्य शब्दावली

ध्यान देने योग्य उच्चारण

इस वीडियो से अभ्यास कैसे करें

इस वीडियो का व्याकरण

शैडोइंग तकनीक क्या है?