Part 3B Flashcards
sampling error
random variability between observations or statistics that is simply due to chance
how to assess sampling error:
sampling distribution
sampling distribution
the distribution of a statistic over repeated sampling from a specified population (a distribution of means)
what is the formal procedure for hypothesis testing?
- start with sample of participants that is the same as a specific population (null hypothesis)
- find out what population does
- compare participants to that standard
how are sampling distributions created?
formed when samples of sample size n are repeatedly taken from a population
properties of sampling distributions of sample means
- the mean of the sample means is equal to the population mean
- the standard deviation of the sample means is equal to the population standard deviation divided by the square root of the sample size n (standard error of the mean)
the Central Limit Theorem
the larger the sample size that we draw from a population, the more normal the sampling distribution of the sample means become regardless of shape of population
Central Limit Theorem: if sample sizes of n greater than or equal to 30 are drawn from any population…
then the sampling distribution of the sample means approximates a normal distribution
Central Limit Theorem: if the population itself is normally distributed…
the sampling distribution of the sample means is normally distributed for ANY sample size n
what is the purpose of hypothesis testing?
to consider the probability that the results of a study could have come about if the experimental procedure had no effect (i.e. if null hypothesis is true)
statistical hypothesis
a statement, or claim, about a population parameter
the alternative hypothesis
the hypothesis that participants did not come from the population of normal responders
the null hypothesis
the hypothesis that participants came from the population of normal responders
null hypothesis and alternative hypothesis must:
COMPLEMENT EACH OTHER
level of significance
maximum allowable probability of rejecting the null if it is true (the point at which the null is probably false) alpha=0.05