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Current time:0:00Total duration:9:34

Video transcript

as we start exploring the world of statistics it's worth asking ourselves what is the word statistics even mean and statistics is really a broad category of things that you might do with data so it generally deals with data collecting data so actually let me write these down it's involving collecting data collecting data you could present data in tables or charts or just as lists of numbers or however you might do it it is analyzing the data analyzing analyzing presenting and analyzing data so this whole class of just you know all the stuff that you might do with data to to answer question or try to figure out what's going on or just to learn about the world that whole class of things is called statistics now an idea that will come up very frequently in statistics is the notion of variability variability and everyday language variability it's - it's it's how much something is how much it doesn't vary how much does it change and it's the same notion statistics in statistics variability is the the degree to which data points are different from each other to the degree to which they vary and just as an example of that just make it a little bit more concrete let's say you were to go to five people and you were to ask them how many how many bricks did you eat yesterday and each of the people say well I know person once if I don't eat bricks at all I don't I don't even know how to do that a brick so the next person says zero the next person says zero fourth person says here and the fifth person says zero fair enough so that was our data point on the different data points on and I'm already doing statistics just by going out there and asking them how many bricks they ate but then I asked them how many how many grapes did you eat yesterday and the first person says i zero grapes but the next person says I survived on grapes I ate two hundred and thirty five grapes the next person says I like grapes I ate 17 grapes then the person after that says that they ate five grapes and the next person also survives on grapes even to a large degree they three hundred and eighteen grapes so if you look at these two datasets one is the number of bricks someone ate yesterday the other one is how many grapes they ate yesterday you immediately see that there's more variability here all of these data points are zero while these they change a good bit from data point to data point so we have a sense that there is more variability in this data set now one of the things we will start doing a lot of statistics is trying to measure how much more how much variability is how can we quantify that how we can we put a number on it how can we measure variability this is a big aspect of Statistics but we won't do that in this video there are future videos for doing that but just as we go into the world of Statistics we should think about well when do we even you know when to should our brain even start getting in statistics mode thinking about the tools that we have at our disposal about collecting data and and measuring variability and measuring and finding numbers that somehow represent a data a pool of data that has variability and so the question we should ask ourselves is what questions in the world are statistical questions so statistical statistical questions so let's come up with a definition for a statistical question the type of question where we would want to start bringing out our statistical our statistical toolkit well one possible way to think about when you need to bring out your statistical toolkit is these are questions that to answer them to answer you need to collect data with variability to answer you need to collect data with variability and apologize for my handwriting data with variability that's w ith data with variability variability so you're saying okay I kind of makes sense but I need to see some tangible questions or examples of things that are statistical questions and things that are not statistical questions and I would say fair enough let's look at some examples so here I have six questions and I encourage you to pause this video right now and before I worked or think about it based on this definition of a statistical question which of these questions are statistical we would require your kind of statistical toolkit and which of these are not statistical so I'm assuming you had a go at it let's go through these one by one so the first question how much does my pet grapefruit way now it's bizarre to begin with to have a pet grapefruit but is this a is this a statistical question what do I need to do to answer it I have to take my pet grapefruit out I have to weigh it and then I have to just write that down and just doing that I am collecting data so you know you could you could argue that maybe I'm kind of starting to mess with statistics a little bit but I'm just getting one data point so I might weigh it and I might see my grapefruit weighs 1 one-pound but that's not data with the variability that's just one data point in order to have variability I have to have multiple data points and should be at least possible that they could vary so for example these all of these folks 8 0 breaks but maybe it was possible that someone actually ate a brick but here I just have one vit one data point with one data point you can't have variability so this is not a statistical question I just collect a data point next question what is the average number of cars in a parking lot on Monday morning well to think about whether it is a statistical question we just have to think about what do I have to do to answer that question well I would have to go out to the parking lot on multiple Monday mornings and measure the number of cars so on the first Monday morning I might see there are 50 cars the next Monday morning I might go out there and count there's 49 cars the next Monday morning I might see 50 cars again the next Monday morning I might see 63 cars so I'm collecting multiple data points to answer this question I'm like then I'm going to take the average of all of these but I'm collecting multiple data points to answer this question and so and and and it's definitely possible that there could be variation here that there could be variability so this is a statistical question next question am i hungry it's an important question we need to ask it to ourselves multiple times in fact sometimes our bodies just tell it to us but I am definitely not collecting I guess you could say I'm collecting some type of feelings from my stomach or week I feel or not but it's definitely not data with variability I'm either hungry or not hungry on a given day I mean if you said broader you know how does my hunger change from day to day and you came up with some type of a scale for raiding your hunger maybe that's more more statistical but just am i hungry a yes/no question this is not this to answer this I do not have to collect data with the variability so this is not a statistical question how many teeth does my mother have to do this I would have to go find my mother and then I would have to ask her to open her mouth and count the teeth in her mouth and maybe I get a number like 30 so it's kind of like how much does my pet grapefruit way I do have to do I have to do I do have to collect one data point but one data point is not going to have variability so I am NOT collecting data with variability so this is not a statistical question if I said how many teeth do all of the mothers that I know have on average or what's the range of number of teeth that the mothers I know have well that that would start getting that or that would be statistical but this is just one data point so not statistical how much time do the members of my family spend eating per year well once again what do I need to do to answer this question well I would have to go either observe or survey my family members you know maybe my mom my wife my children and uncles aunts whoever else I would say well how much do you eat each day I would add them all up to figure out how much they eat of the year and maybe you know family member a eats eight hundred and thirteen hours in a year family member be eight I don't know seven hundred and thirty two hours in the year and so you see the general notion that I will be collecting multiple data points from the different family members and they're very well and in fact there is very likely to be variation in that in fact I might even see variation from year to year person a is probably gonna need a different number of hours in the in the next year so I'm definitely going to collect data with variability in order to answer this question so that is a statistical question and then finally I have the question how many times have I watched Star Wars well this is very similar to how many teeth does my mother have or how much does my pet grapefruit way I just have to count the number of times that I watch Star Wars and maybe you know it's I watched it seven times just one data point no variability here if I said on average how many times have my co-workers watch Star Wars well then I'm going to have to collect data with variability I'm gonna collect multiple data points and it's definitely possible that my co-workers have watched at different numbers of times but for this question in particular was just one data point to answer it how many times have I watched Star Wars and I my answer in this case actually I think is seven well then not a statistical question so hopefully that gives you a sense of statistics variability and what a statistical question even is