Be familiar with the experimental design What are the two important elements of an experiment i e taking action and observing the consequences One group gets the treatment whereas the other group does not Know the scientific experiment notation X the treatment independent variable Y outcome of the variable Z rival casual factor O observation measurement of dependent variable E equivalence randomization or matching 1 2 time points Be familiar with the three major pairs of components in the classical experiment Be able to apply define and apply the three components Independent and dependent variables 2 Pretesting and post testing 3 Experimental and control groups Independent and dependent variables the independent variable takes form of a dichotomous stimulus that is either present or absent IV cause DV effect i e concerning alcohol abuse how often subjects used alcohol is the dependent variable and exposure to a video about alcohol s effects is the independent variable Pretesting and post testing Subjects are initially measured in terms of a DV prior to association with the IV pretested they expose to the IV then they are re measured in terms of the DV post tested differences between the measurements on the DV are attributed to influence of IV Experimental and control groups experimental group exposed to whatever treatment policy initiative we are testing Control group very similar to experimental group except that they are NOT exposed Be able to differentiate between experimental and control groups What is the relationship between experimental designs and causal inference Experimental design ensures what The relationship between experimental design and causal inference is that the researcher is trying to demonstrate a cause and effect relationship Experimental designs ensure that the cause precedes the effect in time by taking post test measurements of the dependent variable after introducing the experimental stimulus Be familiar with the various kinds of threats to internal validity The problem of threats to internal validity refers to the problem possibility that conclusions drawn from experimental results may not accurately reflect what went on in their experiment itself What is the relationship between samples and populations Why do researchers rely on samples What is a sample What is a population The relationship between samples and population is that sample is a smaller version of the population Research rely on sample because they can t collect info from every individual so they rely on samples to get a general idea of what the population is like Sample representation of the population Population the whole group of interest Be familiar with the following sampling terminology variable parameter statistic and sampling error Variable A set of mutually exclusive attributes ex Gender age employment status year of study Parameter summary description of a given variable in a population Statistic summary description of a given variable in a sample Sampling error because our sample will not be exact representation of the population error results we can estimate the degree of error to be expected Be familiar with the two main types of sampling methods Be able to differentiate between nonrandom and random samples random samples each element in a sampling frame is assigned a number choice are then made through random number generation Nonrandom or systematic sampling elements in the sampling frame are chosen systematically for inclusion in the sample ex Picking every 3rd number in a sample What are some of the purposes surveys serve What are the weaknesses of surveys Surveys are used for many purposes Descriptive survey research uses statistical probability to ask whether something that is true of the sample is true of the population Analytic survey research attempts to address issues of cause and effect Weakness of surveys Surveys do not measure directly observed behavior but rather attitudes or claimed behavior What are the two types of survey design questions used in research What are the strengths and weaknesses of the two types of survey design questions Open ended questions advantages greater details in answers Disadvantage hard to code irrelevant answers Closed ended questions advantage easy to code easier for respondents Disadvantage lack of details Be familiar with the two different methods of obtaining data in field research 1 Direct observation 2 Ask questions When is it best to use field research techniques Field research is best to use when topics that can be best understood in their natural settings Ex how street level drug dealers interpret behavioral and situational cues to distinguish potential customers normal street traffic and undercover police officers Be able to identify and differentiate between the various roles of the observer in field research complete participant participant as observer observer as participant complete observer Complete participant participate fully in true identify and purposes are not known to subjects Participant as observer make known your position as a researcher and participate with the group Observer as participant Participants make known your position as a researcher and do not actually participate Complete observer observes without becoming a participant Be familiar with how researchers gain access to subjects Snowball sampling once you re dealing with someone you ask that person to refer another person to you and on and on Be familiar with the central tendency mode median and mean What do they tell us Measures of Central Tendencies Mean median mode What happens in the middle what s happening on average Mode most reoccurring value Median n 1 divided by 2 If there is an odd number of cases the result will be the actual case if there is an even number of cases the result will be between two cases calculate the score that falls between the two cases 15 1 16 2 8 8 is the position of the median The median is 4 review slide for ex 16 1 17 2 8 5 4 5 9 2 4 5 Mean sum all values then divide by of values Ex 572 20 28 6 On average the 20 prisoners sampled had a prison sentence of about 28 6months Mean from frequency distribution N number of values 49 Age x f fx 17x7 119 16x12 192 15x9 135 Etc Add up fx 119 192 135 etc 706 N 49 14 41 the average age of the 49 juvenile offenders sampled is 14 41 Mean for Grouped Sample Ex 30 offenders age at first arrest Class interval 21 23 f 6 18 20 15 17 21 23 2 22 etc M 22 N 30 m f MF 22x6 132 Sum up Mf
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