Inferential Stats/Exp Research (wk 6) Flashcards
Which group (population/sample) contains all subjects of interest?
Population group
Which group (population/sample) gives you the quantity from it, also known as a statistic?
Sample group
Which group (population/sample) is the best approach available?
Sample group
Which group (population/sample) gives you the numerical value of a parameter?
Population group
Which group (population/sample) is a part of selection that is required to be random?
Sample group
Which group (population/sample) is impractical to test every member?
Population group
T/F A sample group does not have to be a good representative of the population group
False, it DOES
Why may a sample not be good even when a truly random sample is used?
- random selection implies that all members of a population have an equal opportunity chosen
- random selection doesn’t guarantee proportional representation of all parts of the population
What is the differences between the sample values and the population values?
Sampling errors
What is the distribution of values taken by the statistic in all possible samples of the same size from the same population?
Sampling distribution of a statistic
What is the distribution of sample means?
Sampling distribution of means (s/square root (n))
where s = sample SD
n = sample size
T/F the sampling distribution of means will be in the shape of the normal curve by Central Limit Theorem
True
Ex: Sampling distribution of means sample of n = 10 mean = 115 sem= 30/square root (10) = 9.5 Interpret this using CI = 95%
95% of the time, the mean might be in the interval
115-29.5, 115+29.5) = (96,134
What is a common inferential stat used to estimate population parameters?
CI
ex: Determine length of hospital stay for patients with LBP from the sampled medical records
WHat is a common inferential stat used to compare between groups?
SHT or CI
ex: Is one treatment more effective than another?
What value will quantify how consistent your sample values are with the null hypothesis?
P-value
a large p-value closer to 1 -
your sample values are consistent with the null hypothesis
a small p-value closer to 0 -
your sample values are not consistent with the null hypothesis
alpha = .05, p-value
leads you to reject the null hypothesis - observed difference shows significant effect
alpha = .05, p-value >.05 leads you to do what?
leads you to retain the null hypothesis - observed difference is probably due to chance and is not significant
What is a range of scores with specific boundaries, or confidence limits?
CI
CI can be used to do what two things?
- estimate population parameters : lumbar spinal extension for 30-39 year old individuals is from 37.3 degrees to 42.7 degrees
- compare between groups:
- the mean difference of SBP between the group with the new medication and the group with the standard treatment was 10 and its 95% CI was (5.1, 15.7)
- the odds ratio of having breast cancer for the group physically active over the group not physically active was 2 and its 95% CI was (0.5, 4.5)
The narrower CI implies ____ precision and ___ variability
higher precision and less variability
The wider CI implies ____ precision and ___ variability
lower precision and increased variability