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  2. Cox's proportional hazards model - Commonest approach to model survival or time to event data. - It's analogous to a multiple regression model, and tests the difference between survival times of particular group, while allowing for other factors. - In this model, the dependent variable is the 'hazard', which is the probability of dying (or experiencing the event in question), given that patients have survived up to a given point in time, or the risk for death at that moment. - No assumption is made about the probability distribution of the hazard. - However, it is assumed that if the risk for dying at a particular point in time in one group is, say, twice that in the other group, then at any other time it will still be twice that in the other group. In other words, the hazard ratio does not depend on time. The hazard of failure in one group is a constant ratio (over time) of the hazard of failure in the other group. Log rank test does not assume proportional hazards per se. - Used to compare 2 survival curves, and tests whether there's a difference between the survival times of different groups. However, it does not allow other explanatory variables to be taken into account. - It's used to test the null hypothesis that "there is no difference between the population survival curves" (i.e. the probability of an event occurring at any time point is the same for each population). - It's the most powerful for detecting alternative hypotheses in which the hazards are proportional. Quick Reference: http://thestatsgeek.com/2017/09/21/survival-analysis-power-log-rankcox-versus-rmst/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1065034/
  3. My shortcut to remember subtypes of criterion/construct validity: CONstruct validity: CONvergent & divergent Criterion validity: Concurrent & predictive
  4. I remember them this way and I think it's easier to understand. Sensitivity (e.g. of a screening test) Among those with the disease, how many will be correctly screened as positive? Specificity Among those without the disease, how many will be correctly screened as negative? Positive Predictive Value Among those who were screened positive, how many actually have the disease? Negative Predictive Value Among those who were screened negative, how many actually don't have the disease? Hope this helps
  5. Performance bias - Happens when one group of subjects in an experiment (e.g., a control group or a treatment group) gets more attention from investigators than another group. - Can also refer to the fact that participants can change their responses if they know which group they are allocated in. (A set of Hawthorne effect) Observer bias (also called experimenter bias or research bias) - Tendency to see what we expect to see, or what we want to see. When a researcher studies a certain group, they usually come to an experiment with prior knowledge and subjective feelings about the group being studied.
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  7. Hi hi I know I'm 6 years late but just wanna try answering the question Chi-square is really just a special case of logistic regression, and this is analogous to the relationship between ANOVA & regression. (Ref: http://web.pdx.edu/~newsomj/pa551/lectur21.htm) Chi-square contingency analysis: - Independent variable is dichotomous - Dependent variable is dichotomous - Purpose: Used to determine whether there's significant difference between expected vs observed frequencies in one or more categories. Logistic regression is a more general analysis, because: - Independent variable is not necessarily dichotomous, and can have >1 independent variable. - Dependent variable (outcome) is dichotomous - Purpose: Predicts value of a dichotomous dependent variable (outcome) by using 1 independent variable & a constant. - E.g. How does the probability of getting lung cancer (yes vs. no) change for every additional pound a person is overweight and for every pack of cigarettes smoked per day? Here, outcome is dichotomous (gets lung cancer vs not getting lung cancer); there're >1 independent variables (weight & packs of cigarettes smoked per day). References: https://www.statisticssolutions.com/what-is-logistic-regression/ https://en.wikipedia.org/wiki/Chi-squared_test#Example_chi-squared_test_for_categorical_data
  8. General rule: Positive Predictive Value (PPV) increases with increasing prevalence. Negative Predictive Value (NPV) reduces with increasing prevalence. In this case, urban had higher prevalence. Thus, urban should have higher PPV, lower NPV. Rural should have lower PPV (option A is correct), higher NPV. Explanation: PPV = Out of those who were tested positive, how many actually had the disease? Thus, prevalence affects the PPV calculation. Sensitivity = Among those with disease, how many will be tested positive? So it doesn't actually matter how many ppl have the disease (prevalence is not important). The important point is, how many ppl will be tested positive.
  9. La Casa De Papel aka Money Heist on Netflix!
  10. Hi

    I hope you are well. sorry for the random message.

    I noticed some of your paper B posts. I have the exam in 3 weeks time- and wanted advice about prep? which questions banks/notes would you recommend?.im very bad with stats/ c appraisal

    many thanks

  11. Any one want to creat a study group what's app to help each other gathering and sharing information or sharing costs please contact me on what's app number +201553930314. Thanks in advance
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  13. Please add my number 0044-7412049949
  14. Has anyone appeared for General adult interview, could possibly guide me on this scenario- Thanks! You are an ST4 in Psychiatry in a community team. A care co-ordinator informs you that Sam, a carer, is in reception appearing anxious and distressed. He/she is demanding to see a senior doctor and has a complaint following a consultation with a CT1 doctor last week. Sam’s son Adrian has just recovered from a first episode psychosis and was discharged one month ago after admission under the Mental Health Act. Following last week’s consultation he is refusing medication Olanzapine due to worries about weight gain. You have Adrian’s permission to talk to family. You have 15 minutes with the carer, but you can finish earlier if you choose to do so.
  15. Can anyone help. How many preferences should I put in my options. And out of no preferences will they allocate anyone or in a particular order from top to bottom. Also if I am offered a post which I don’t like can I decline it. Will I get more offers then.
  16. i have cleared my neetpg this year(its an exam to get pg in India) and can join MD in psych. im confused about my further oppurtunies as im not sure if i want to stay in india or not.. what is to be done after my MD will my degree be valid in UK or anyother country???
  17. i have finished my mbbs in india, and very keen about psych. i have heard its easy to get into NZ after doing MD in psych, in india than going after mbbs.. i have cleared neetpg this year and can take up MD psych, in india right now im a little confused what do i do?
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  19. For people who find the stats calculations tricky this app can really help. It has a worked maths question at the end of each round
  20. Hi George, I'm surprised they found you partially comparable as with experience they should give you specialist status. Did they say why? My understanding is that they consider specialist with experience of more than 2 years. If feasible,give another ago after some time. Kind Regards, Cata
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  24. Dear colleges I just start working in Psych ward, and I am planing to apply for training. I want to start reading to know psych more, please would you suggest a book that will enhance my knowledge in psychiatry, Thanks.
  25. Hi i can see see this is a very old and useful post. The link u have mentioned : drscotthall doea not seem to be working. Any chance u have the pdf ? thanks
  26. Hi, I have been found partially comparable despite having CCT and MRCPSYCH, and 1.5yrs consultant experience, I am getting somewhat worried about the OSCE and the essay style exam. Any words of advice, a couple of colleagues told me to just drop the whole Oz plan. I'm not sure any more...
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  28. any active whatsapp group for those who are appearing in june 2019 ?
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