Collecting data
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| Population: | The entire group we want information about
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| Sample: | A REPRESENTATIVE of the population
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| What do we want the sample to be? | (blank)
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| What is an important characteristic of a random sample? (The Most Important) | Each item must have an equal change of being selected
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| Observational Study: | We just observe individuals and measure variables of interest, we don't influence a response
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| Experiment: | The researcher imposes a treatment on individuals to observe response. Usually COMPARES
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| What is the goal of randomization? | create groups that are as similar as possible before treatments
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| What does normalization or having a bell shaped curve imply? | randomization, having similar groups
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| What is blocking? | Seperating objects into similar groups so no confounding occurs
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| When is an event considred random? | individual outcomes are uncertain, but pattern emerges in long run
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| What is probability? | Measures the likelihood of a random event
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| Relate probabilty and randomness to a coin toss | A coin toss is random because in the long run, we expect a 50% distribution, so the probability of this is 0.5 because we expect about half of coin tosses to be heads
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| Parameter: | Any number that describes a population
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| Statistic: | Any number that describes a sample
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| What is important to note about parameter-population and statistic-Sample? | The first letters match and that's how to remember them
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| What are the two concepts most important to note about probability? | Individual outcomes are uncertain, a pattern emerges in long run
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| What is the sampling distribution of a statistic? | Distribution of all possible values the statistic could have in all possible samples of same size and population
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| What is the Central Limit Theorem? | Provided that n is large, the sample will have a normal distribution with the same mean as original distribution and s.d = sigma/radical n
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| WE DON'T REALLY CARE ABOUT POPULATION DISTRIBUTION | (blank)
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| What is a simple Random Sample? | Two steps 1)Label everyone 2) Use Table B
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| Bias: | Favors certain outcomes
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| What are the types of bias? | Voluntary sample and convenience sample
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| Treatment: | Experimental condition applied to subjects
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| Comparative experiment: | Compares two groups
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| Control: | Receives sham treatment
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| Why are experiments better than obsevational studies? | Observational studies can have lurking variables to cause confounding
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| Probability sample: | A known chance over zero of being selected
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| Stratified Random Sample: | Divide population into groups of similar individuals (strata), choose SRS from strata, combine for full sample
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| Factors: | Explanatory variables (dose of drug)
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| Level: | Subdivision of factor
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| Randomization | Use chance to divide experimental units into groups
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| What is the logic of Randomized Comparative Experiments | 1) Random assignment = groups similar in all respects b4 test 2) Comparative design = outside influences equal to all groups 3) Differences in average response due to treatment or play of chance in the random assignment of subjects to treatments
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| What are the three principles of experimental design: | Control (lurking variables) 2)Randomization 3)Replication (more tests less chance of variation)
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| Block: (Example) | Experimental units or subjects known to be similar enough to affect response to treatment prior to experiment's run (Luxury cars)
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| Matched pairs: | Common form of blocking for comparing two treatments
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| Sampling Variablility: | Statistic varies in repeated random sampling
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| Law of large numbers: | Random observations from any population with finite mean (u). As observations increase, the mean X of the sample gets closer to mean U of population
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| What does sampling distribution mean in ENGLISH | Ideal pattern that would emerge if we looked at all possible samples of n we take.
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| Four aspects of Sampling distributions: | 1)Identify parameters and statistics in a sample or experiment 2) Recognize sampling variability: different values after repetition 3)Describes values taken by statistic in all possible repetions under same conditions 3)describe problites of possible valu
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Created by:
talkglitter2486