Understanding Standard deviation and other measures of spread in statistics
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- Опубликовано: 21 авг 2024
- Dr Nic explains the three measures of spread, range, inter-quartile range and standard deviation. This is part of a series of videos for introductory statistics. It uses real data collected from students about the number of pairs of shoes they own.
See creativemaths.... for all of Dr Nic's videos organised by topic.
Hi DrNick, thanks for the simple explanation, I have some clarification regarding the spread. In the inter-quartile-range do we have to take 1/4 of the data to find the range ?. Please explain it in more simple definition.
The quartiles are found in a similar way to the median. For example if you have 29 observations, put in order, then the 15th observation is the median, the 8th observation is the lower quartile and the 23rd observation is the upper quartile. There are several ways of dealing with even numbers of observations and not all sources agree on it. I use what the computer gives me. We do have a video about boxplots that you can see if you become a channel member.
A word to the wise, this video does a very poor job of explaining inter quartile ranges, quartile, etc. The channel is usually quite good for basic stats concepts but this particular video jumps over concepts that most non stats nerds struggle with. It’s not you, it’s this video. Do a RUclips search for a better explanation and the. Return to this channel for some of the other topics
Thank you for a wonderfully clear explanation. When would we use IQR vs. standard deviation to measure variation? Are there pros and cons to using each? And what is the value of knowing that there is more variation in women's shoes than in men's shoes? How can we use that insight?
IQR is more intuitively understandable than the standard deviation, but standard deviation is used a lot more as it has useful mathematical properties. Knowing that there is a wider range in the number of pairs of shoes women own, might mean that you use more than one marketing approach - to those that own a lot and to those that don't own many. For the men there isn't the same spread, so you might not segment the market. Not really a sensible example, but I had real data available and shoes aren't too difficult to draw.
And thank you for your support as a channel member!
Hi Dr Nic, thanks for another great video. I've just watched the one on confidence intervals and now I'm a little confused. What is the difference between standard deviation and confidence intervals? When and why would we use each of these?
A standard deviation is a measure of the spread of a sample or a population. It tells us how spread out the data is, and we would expect nearly all values to occur within 3 standard deviations up or down from the mean.
A confidence interval is used to express what we can say about a population from a sample - which is known as inference. Confidence intervals can be calculated for many different statistics, including the standard deviation. The formula for the confidence interval for a mean uses the sample standard deviation as that tells us how spread out we would expect our sample means to be.
I suggest you watch a few more of the confidence interval videos as it takes a bit to get your head around.
good video
Thanks
How to calculate inter quartile range ? And please explain about box plot how to view ?what it shows.
The quartiles are found in a similar way to the median. For example if you have 29 observations, put in order, then the 15th observation is the median, the 8th observation is the lower quartile and the 23rd observation is the upper quartile. There are several ways of dealing with even numbers of observations and not all sources agree on it. I use what the computer gives me. We do have a video about boxplots that you can see if you become a channel member.
Can suggest good book. To follow your vedio one by one.
It will help us future understanding
That is a good question. We are working on having a systematic approach to our videos. For now you might find this helpful: creativemaths.net/blog/videos-for-teaching-and-learning-statistics/
IN response to your request we have made this set of webpages: creativemaths.net/videos/ that will take you systematically through the videos. If you join the channel, you will also be able to ask for help. ruclips.net/channel/UCG32MfGLit1pcqCRXyy9cAgjoin
Is there a way to calculate the standard deviation?
Yes - wikipedia will tell you the formula. I would use a computer app.
How to find outliers and confidence interval?
There are several videos about confidence intervals. I have not yet made videos about outliers.
range quantile deviation
Huh?
Got me on RUclips trynna figure this out n shit
Be little slow while explaining the concepts , ur rushing up ..
Feel free to pause or slow down the video to suit you.