huong dan thuc hien nghien cuu khoa hoc suc khoe

GS TS BS LÊ HỒNG NINH NGHIÊN CỨU LÀ GÌ ?  Research is the systematic collection, analysis and interpretation of data to answer a certain question or solve a problem  It is crucial to follow cascading scientific steps when conducting one’s research Qui trình nghiên cứu khoa no need for học study Selection of area Selection of topic answers found Crude research question Literature no answerreview Refined research question Research hypothesis, goals and objectives Study design Population & sampling Variables confounding Research tools Pilot study Work plan Collection of data Data management Interpretation Reporting Ethical issues bias Thiếế t kếếnghiến cứu Descriptive studies Case report Analytical studies Observational studies Experimental studies Randomized Controlled Clinica trials Case serial reports Cross-sectional studies Ecological studies Case-control studies Cohort studies Prospective Retrospective (historical) Randomized Controlled field trials Non-randomized experiments Chọn lựa thiêế t kêếtốế t nhấế t  Purpose of the study  State of existing knowledge (in relation to study question)  Characteristics of the study variables  Latency  Feasibility Mục đích nghiên cứu  Study of etiology:      Ecologic Cross-sectional Case-control Cohort Intervention  Study of therapy:  Lab experiments  Clinical trials  Community intervention Hiện trạng kiêế n thức có vêềcấu ho ỏi nghiên cứu ?  New idea:   Ecologic Cross-sectional  New hypothesis:   Cross-sectional Case/ case series report  Newly claimed association:   Case-control: replication, confirmation Cohort: stronger evidence towards causation  Confirmed association:  Experiment/intervention: to prove causation Đặc điêỏ m biêế n sốếnghiên cứu  Very rare exposures: case-control design is NOT suitable since it looks for exposure A very large number of subjects is required  Very rare disease: cohort design is NOT suitable since it looks for outcome Follow-up of a huge number is required  Acute disease: prevalence studies are not suitable  Risky exposures: clinical trials are unethical  Unavailable data: record-based studies are not suitable Latency  For diseases with very long latency, the costs of concurrent cohort studies or clinical trials are prohibitively high Tính kha ỏ thi  Time  Manpower  Equipment  Money Sai lệch thiêế t kêế Selection bias  Selection bias is a distortion of the estimate of effect resulting from the manner in which the study population is selected  This is probably the most common type of bias in health research, and occurs in observational, as well as analytical studies (including experiments) a Prevalence-incidence bias  This type of bias can be introduced into a case-control study as a result of selective survival among the prevalent cases  In selecting cases, we are having a late look at the disease; if the exposure occurred years before, mild cases that improved, or severe cases that died would have been missed and not counted among the cases b Admission rate (Berkson’s) bias  This type of bias is due to selective factors of admission to hospitals, and occurs in hospital-based studies  The diseased individuals with a second disorder, or a complication of the original disease, are more likely to be represented in a hospital-based sample than other members of the general population  Differential rates of admission will be reflected in biased estimates of the relative risks  Non-response bias  This type of bias is due to refusals to participate in a study  The individuals who not participate are likely to be different from individuals who participate Nonrespondents must be compared with respondents with regard to key exposure and outcome variables in order to ascertain the relative degree of non-response bias  Ascertainment or information bias Information bias is a distortion in the estimate of effect due to measurement error or misclassification of subjects according to one or more variables  Measurement bias  Observer variation bias  Intra-observer variation  Inter-observer variation  Subject (biological variation)  Technical method error variation  Sai lệch nhớ lại (Recall bias)  An error of categorization may occur if information on the exposure variable is unknown or inaccurate  The recall by both cases and controls may differ in both amount and accuracy Cases are more likely to recall exposures, especially if there has been recent media exposure on the potential causes of the disease  Example: In questioning mothers whose recent pregnancies had ended in fetal death or malformation (cases), and a matched group of mothers whose pregnancies had ended normally (controls), it was found that 48% of the former, but only 20% of the latter reported exposure to drugs Kêếhoạch làm việc “State in specific steps what exactly will be done”  Method:  Listing the activities related to the     study (planning, implementation, results) Identification of the responsibility for each activity Setting time and date for achievement of each activity Putting all these elements together in a legible form which could be a chart (GANNT chart) or a table Budget and any funding agencies Cơng việc hành Administering the Research • • • • Informed consent Clear instructions Debriefing Confidentiality Xưỏlý / phấn tích liệu  Data management is the whole process of Data management dealing with data from the very beginning of the study Data analysis is just the last part of it  It can be divided into the following phases:  Preparation of data entry  Data entry  Data analysis  Preparation for data entry:  Review of questionnaire forms  Unique I identifier  Coding  Preparation of master-sheets (manual) or spread-sheets (computer)  Dummy tables  Quality control  Data entry  Phân tích liệu:  Descriptive:  Tabular presentation  Frequency distribution tables  Cross tabulations  Graphic presentation:     Bar charts Pie charts Line graphs Others  Numeric presentation:  Percentages and percentiles  Measures of central tendency  Measures of dispersion Phấn tích liệu ( t.t)  Analytic: The researcher uses principles of biostatistics to test his hypothesis Detection of proper statistical test depends on:  The objective of the study:  Descriptive  Looking for a difference  Looking for an association  Type of variable:  QT  QL  Distribution of the variable:  Normal  Binomial  Poisson  others Lý gia ỏi kêế t qua ỏ  Discussion of the results in a way that relates data obtained to each other clarifying the associations and other findings Reporting comes next ... crucial to follow cascading scientific steps when conducting one’s research Qui trình nghiên cứu khoa no need for học study Selection of area Selection of topic answers found Crude research question