[Music] if you're studying for the inbde I highly recommend inbde boot camp an all-in-one study resource that will help you pass your exam use coupon code mental Dental for 10% off hey everyone Dr Ryan here and welcome back to our biostatistics series I'm excited to present 10 practice questions from this first chapter of the biostatistics series because I think there's so much here that is important and relevant to know for your board exam whether it's the inbde or the Adat or the AFK biostatistics is a really popular and also really difficult section and so I want to make sure we have an opportunity before we get too far into it to test what you've learned up to this point and just so you know what's coming up uh for the future of this series this first chapter has basically been an introduction to the topic the next chapter that we'll dive into is going to be all about study design the types of studies and things of that nature and then the Final Chapter will be on data interpretation where we talk about the measurements and statistical significance what a forest plot is all of that good stuff so this will be the part one of our practice questions for biostatistics covering the first four videos of this series so practice question number one consider the following research question does using an electric toothbrush reduce plaque accumulation and gingivitis more effectively than using a manual toothbrush in adults after 3 months using the Pico framework what is the I in this study so go ahead pause the video think through this question and then we'll go over it together all right so Pico of course is the acronym that we use to formulate clinical research questions and so p is our population patient or problem I is the intervention C is the comparison or control and O is the outcome so we can do this quickly in our research question here we have adults which is our P so we can rule out answer Choice C we have a reduction in plaque accumulation and gingivitis after period of 3 months so that is most closely representative of our answer Choice D so we could rule that out as well and we're left with I and C our intervention and our comparison which happen to be the last two answer choices we have here so an electric toothbrush is the intervention that we're using and comparing to the manual toothbrush so electric toothbrush is going to be our intervention because we're assessing if it's more effective than comparing to the manual toothbrush use so the I in this study is going to be answer Choice a using an electric toothbrush practice question number two which of the finer criteria is related to IRB approval and IRB standing for institutional review board so go ahead and pause the video think through this question and then we'll go over it together so the finer criteria is an acronym used to assess the quality of a research question and all of the finer criteria are listed out in order as the answer choices I also of course memorize what the acronym stands for in case they just straight up ask you what does the n stand for in the finer criteria or what does the r stand for for example but in this question we're trying to figure out which one has to do with with approval by the institutional review board well this is responsible for assessing the ethical nature of a paper whether it's fair and considering the rights of all the human subjects and so IRB approval is necessary for all papers that are going to include human subjects before that paper is published so the correct answer for this question is D ethical practice question question number three which section of a research paper often includes information about future research so go ahead and pause the video think through this question and then we'll go over it together so for A Brief Review the introduction section is providing background information about the topic that we're discussing in the study and in the paper the method section describes how the study was conducted in very exact terms the discussion section interprets the findings of our study and the conclusion section answers the original research question that was posed in the abstract and also at the end of the introduction and so the best answer for this one is the discussion section this is where we interpret the results but we also explain their significance and place them in the context of existing knowledge the section outlines gaps in Knowledge Questions that remain unanswered and areas that could benefit from future research so the answer to this question is C practice question number four which of the following is an ordinal variable so go ahead and pause the video think through this one and then we'll go over it together all right so now we're covering topics from the second video in the series on variables so here we have eye color blood type zip code and socioeconomic status well first ey color is a variable that has many different values it could be brown blue green Hazel Gray Amber but those are not ranked in any particular way there's no order to those eye colors so that is a nominal variable not an ordinal variable blood type is the same it has multiple different options a b a and o but there's no rank or priority or sign ific an order to those so B is also a nominal variable and then we have zip code which could be many many different options and again there's no order to them even though they are technically numbers there's no order to those numbers and so C is also a nominal variable and lastly we have D socioeconomic status which is ranked from Low Middle to high so there is a meaning behind the the ranking or an order to those values and so D is an ordinal variable and the correct answer as well practice question number five which of the following statistics can be applied to nominal data so go ahead pause the video think through this one and then we'll go over it together so the three main types of descriptive statistics which we're going to review in much more detail later are frequency distribution central tendency which includes mean and median and variability of a data set which includes standard deviation but I did mention these topics in a table where we talked about nominal ordinal interval and ratio variables and as you go from left to right in that table you have more and more possible statistics that you're able to use with those variables and the values that they bring and so nominal is going to be the most restrictive of all of that data for example in order to calculate the median you need at least ordinal data ordinal interval or ratio will suffice but nominal doesn't work just think about if you had blood type as an example you can't have a on one end and then AB on the other end and then you have o in the center and so there's no way to calculate a true median or any kind of central tendency of that data set and then even more so we need at least interval data to have a mean or standard deviation because then we need actual numbers that you can add together and divide and do all sorts of things with so mean and standard deviation need at least interval if not ratio variables involved and so all of those are ruled out as then is e so we're left with a frequency distribution which is the only statistic the only descriptive statistic that you can calculate from nominal data so the answer choice that is correct for this one is a practice question number six you have the following researchable question that you'd like to pursue with a clinical study is mandibular fracture more likely to occur during a bis sagittal split osteotomy if third molers are present evidence indicates that fractures in general are more likely to happen in females and as individuals age so which of the following would be the predictor variable in your study so go ahead and pause the video think through this question and then we'll go over it together so the topic here is once again variables this time we're considering more the operationalization of those variables what is the predictor variable in our proposed study question and interestingly we we did some background research here we got some evidence from previous studies that may influence the outcome of our study so we're already considering some possible research bias here which is a great first step to designing a powerful research study now you can see with the question here I called it a researchable question because it's not really a research question in terms of the Pico framework we don't have a population for example specified but that's okay this is the first step of a nent research project and so you can see that everyone that we're looking at here is going to have a bis sagittal split osteotomy otherwise the research really isn't going to to work at all so a bsso here is basically a constant all of the human subjects would have this and nothing changes about it so this is not a variable at all we can rule out a from the possible choices remember back to my diagram with the watering can the plant and the Sun so the watering can was our independent variable it was the thing that the researcher could manipulate this is also called the predictor variable which is what we're looking for here here so what we can control is if third molers are present or not so well basically if I'm designing This research project have two separate treatment groups one with third molers and one with third molers extracted and then all of those subjects in both treatment groups would undergo the bsso granted that's what they're going to have done anyway so they're going to be included in the research project so the predictor VAR the thing that is going to change that we can manipulate is whether or not they have third molars present so that is our predictor variable now just to take this all the way through the outcome variable or the dependent variable is the plant what's going to change as a result of manipulating this part and so that's going to be whether or not mandibular fracture happens of course we hope there's no mandibular fracture but sometimes it is a side effect so that is going to be the the outcome variable in this study and then we had mentioned from previous studies that the sex of the patient and their age could potentially impact the incidence of mandibular fracture and so these I would consider as confounding variables like the sun in our plant study example from the second video in this series so sex of the patient age of the patient maybe ethnicity of the patient all of these are possible confounding variables in this study so again predictor variable is presence or absence of third molars which is the correct answer outcome variable is mandibular fracture confounding variable is age of the patient and then the bsso procedure is simply a constant in this study design practice question number seven which of the following is the strongest sampling method go ahead and pause the video think through this question and then we'll go over it together so now we're talking about content from the third video in the series on sampling and allocation and there I talked about how sampling is selecting individuals from a population to be included in your study sample and then allocation after that is how those sampled individuals are assigned into different groups so for sampling of course if we could do a census where we can include everyone in the Target population that would be awesome but usually it's not possible so the strongest sampling method from there is one that involves random sampling and that would be a probability sample so the answer for this one is in fact answer Choice C the other ones are nonrandom sampling which isn't quite as strong sometimes it's easier but they are weaker sampling methods consecutive is the best of the non-random that's where you take individual in a certain order as they come into an event or a room or a clinic convenience is picking people because they're just present they're easy to get like people at a dental convention or in a classroom and then judgmental is the last one this is where it's really biased because you're intentionally picking people who are easy to work with or trusted friends or family or colleagues people you know who aren't going to drop out of the research study so they can be reliable subjects that would be definitely the weakest sampling method on the list but again the answer for this question is C practice question number eight so I'm going to let you guys pause the video and read through this one on your own take your time think through the answer choices and then we'll go over it together so here we have a research study that's evaluating the efficacy of a new fluide mouthwash compared to a place mouthwash so this is a pretty classic design for what would be considered a randomized control trial we'll talk more about those study designs in the next chapter of this series but all we need to know here and all we're being asked is the sampling and allocation method that would be best to ensure that the study results are generalizable and applicable to the Target population of teenagers so when we look at these answer choices some of what we talked about in the last question applies here as well so we're really looking for the most random sampling and random allocation methods to help get the strongest study design and minimize possible bias so for this one I would just rule out all of the answer choices that involve something that's not random so for example convenience sampling is not random convenience sampling again is not random and then we have non-random allocation down here which could be by convenience or by clinician choice and so we're left with answer Choice B which involves both simple random sampling and random allocation so that would be definitely the strongest sampling and allocation design of the list so the correct answer for this one is B practice question number nine which of the following strategies is best suited to reduce the potential for recall bias go ahead and pause the video think through this question and then we'll go over it together so now these last two questions are going to have to do with the fourth video in the series on Research bias so if you remember my memory tip for this one recall is most common for retrospective studies because the subjects are being asked to recall something from the past so the best way to minimize this type of bias is to reduce the amount of time between when something happened and when they're being asked about it so that would be answer Choice C decreasing the time from the exposure to the follow-up the exposure being when something happened to them the follow-up being when they're asked about it so the answer for this one is C just for review purposes randomization is best to help reduce confounding bias blinding is best to reduce expectation bias and calc calculating age adjusted survival rates that's actually the strategy to reduce lead time bias so all of these methods are actually great for reducing bias in your study but C is the one specifically for recall bias and finally practice question number 10 which type of bias does the Hawthorne effect fall under go ahead pause the video think through this one and then we'll go over it together so the hawthor effect is a type of human behavior in which individuals modify their behavior in response to an awareness of being involved in a research study so this is most closely associated with Observer Bias where study participants behave differently knowing that they're being observed in a study so how'd you do let me know in the comments how many of those 10 practice questions that you got correct thank you so much for watching this video and watching this series so far I'm looking forward to continuing with the next video on types of studies so until next time keep working hard and if you need to feel free to go back to some of those earlier videos in this biostatistics series to clarify some topics or areas based on how you did with the practice questions so that you have a very clear perfect understanding before diving into deeper areas of biostatistic itics so we'll see you next time thanks so much for watching that's it for this video lecture thank you so much for watching I genuinely appreciate it I'd also really appreciate if you consider clicking that like button below this video subscribing to the channel if you have not already sharing this video with your friends and leaving a comment below letting me know what you thought all of those things can really help to grow the channel if you want to go above and Beyond supporting me and what I do here please check out the patreon page linked below if you want to join there you'll get access to exclusive practice questions exclusive study guides a Discord server and so so much more and if you see at the end of my videos I have an end credits screen and all of those names there are the names of my amazing patreon supporters that I'm honored to have thank you again for watching and I'll see see you in the next video [Music]